Among the reasons for these crushes, certainly, is convenience. “You have this stationery target for your affection,” says Jim Behrle, a currently unemployed 31-year-old who used to work at a bookstore and also lives in Boston, of his fondness for coffee shop baristas. “They’re sort of stuck behind the counter and have to be nice to you.” There’s also the plausible deniability quality of the flirtation: If you strike up a conversation with someone on the subway or in a bar, you’re hitting on them. But if you chat with the deli guy as he slices your smoked turkey, well, you were just being polite.

If the objects of the crushes are in the food service industry, particularly if they’re waitresses, they seem both sexy and comforting. “In the public consciousness, in TV and films, waitresses are needy, a little sexually promiscuous — a lot of them are single moms — and they have a heart of gold,” says Debra Ginsberg, 42, a waitress for 20 years and the author of “Waiting: The True Confessions of a Waitress.” “They’re providing food, which satisfies this basic need, but [sometimes] they’re wearing provocative outfits.”

Then there’s the possibility of the hourly wage earner’s “hidden depths,” as Jim, the barista fan, terms it: the disparity between what that person is doing (serving you a beverage, for example) and what that person is actually capable of (who knows?). In other words, a bartender who went to Harvard Law School is for some of us more intriguing than a lawyer who went to Harvard Law School.

The customer service crush often goes unrequited — at one fancy restaurant where Debra was a waitress, she wore “a pinafore and ugly shoes and a tie, and these 80-year-old dudes would be smacking me on the ass” — but reciprocation isn’t necessarily the point. Jeremy Jackson, 31, a novelist and food writer living in Iowa City, sees most customer service crushes as a form of entertainment during otherwise dull errands. “They’re crushes of daily commerce,” he says of the hippie-sexy cashiers at his local cooperative food market. “I wouldn’t have the crushes except that I happen to be there every day.” Increasing the illusion of chumminess, these cashiers’ names are printed on the bottom of receipts, and, as Jeremy explains it, “The narrative of the new girl at the co-op is that they’re really cute and nice at first. Over the months, they get worn down by the job. But then, of course, there’s a new co-op girl. I can go in and there are layers upon layers of old co-op cashier crushes.”

A more serious customer service crush reared up for Jeremy at an Indian restaurant a few years ago. The waitress “had short dark brown hair and was kind of pixie-esque but not too pixie-esque. It was one of those crushes that snuck up on me — a few days later, I was like, hey, I could go back and see that waitress.”

He devised a plan: “I would go by the restaurant, which had big plate glass windows in front, and I would walk really slowly and look in as casually as I could, hoping to catch a glimpse of this girl. Once I figured out that she worked on Tuesdays, I went in and sat down — and she wasn’t there! I had to sit and eat a whole damn dinner by myself, and I had brought these props, like an issue of Harper’s that I didn’t want to read. [I'd planned to say,] ‘Oh, excuse me, let me move my issue of Harper’s so you can put my meal down,’ and then she’d say, ‘I love Harper’s!’ But she wasn’t there and I got served by the typical 52-year-old Indian guy.” Adding insult to injury, the food that night wasn’t even very good. After the meal, Jeremy officially retired his crush.

Rich, the outdoor gear fetishist (who didn’t want his last name used), successfully got to the stage of asking out his customer service crush — but he didn’t get much further. After dropping by the EMS store a few times, “I went back with the intention of asking her to go kayaking — I thought that was appropriate given the theme of the store — and we started chatting, but some middle-aged woman came over and dragged her away because she had to buy her son a sleeping bag. It totally took the wind out of my sails.”

Not for long, however: Propelled by the memory of how good Ms. EMS looked in her store-issued green apron, Rich returned when he knew she wouldn’t be working and left a note with his phone number. Ms. EMS did indeed call Rich and they made a date to kayak but, Rich says, “Then she bailed the day before because she said she had to go to a funeral. We tried to make another plan, and she bailed on that, too, and I was like, OK, I’m getting a sense of what’s going on.”

Several months had passed, and Rich had begun dating somebody else when Ms. EMS called him one day — while he was eating lunch at a Chinese restaurant with his new girlfriend. “At that point, I’d lost interest,” Rich says. For a period, he even stopped frequenting EMS, highlighting the dark, or at least the awkward, side of the customer service crush: the self-enforced boycott of a place where you might even kind of need to shop. “And then about three weeks ago, I decided to be a grown-up and go back in there,” Rich says. “Of course, who do I run into in the water bottle section? I looked at her and she looked at me — I’m sure we both knew who it was — and I just went back to looking at the water bottles.”

Rich could take a lesson from Jim, who describes himself as a “connoisseur of crushes” and keeps lists of his weekly top 10 love interests on his blog. The customer service crush, Jim argues, is doomed to fail if pushed beyond its place of origin. “When you bring them to fruition or take them out of the world of fantasy, it’s like stapling a butterfly to a desk,” Jim says. “There’s no way it will continue to be a butterfly.”

Indeed, the beauty of a customer service crush can be its very lack of seriousness. “It’s not like, ‘I have to go to her parents’ house and hang out with her dad,’” Jim explains. The crushes are “a sugar burst — instead of having to chew the gum all the time, you chew it while it’s fun, and then when it’s not fun, you don’t go into that bar for a year and a half.”

Debra Ginsberg, the author and former waitress now living in San Diego, agrees that the customer service crush is often a fantasy — or, seen from the employee’s perspective, more of a nightmare. “How can this person really be into you after you serve him a bowl of minestrone?” she asks. “He’s got some fantasy that has nothing to do with who you are. Especially if they leave their phone number and a bad tip — it’s like, ‘Dude, think again.’”

Against her better judgment, Debra did once, in 20 years of waitressing, agree to go out with a customer. “It was an absolute disaster. He was psychotic,” she says, adding that “the best policy is to date people you work with because those are people you see every day and you know what they’re about. That’s why you often have people in a restaurant having sex with each other in the storage room.”

Until a few years ago, Jim usually set his sights on bartenders. “You get progressively more ridiculous as the night goes on — you’re pretty much handing out money to these people because you’re completely in love with them. You get a $2 Pabst Blue Ribbon and it’s like, ‘Here’s a five, keep it — I just want you to be happy.’”

Although he no longer drinks, Jim says, “There’s something erotic about people who present you with the things that you’re addicted to” — and caffeine certainly counts, which is why Jim stops by at least two coffee shops a day. Even when it comes to latte, apparently, the personal is political. “There’s camaraderie between people who have crappy jobs,” Jim says. “They aren’t expecting you to take them out for caviar or to go yachting. If you leave Sweet Tarts in their tip jar, they’ll be like, ‘That was the nicest thing anyone’s ever done for me!’”

Perhaps it’s that intoxicating sense of being appreciated that at times causes the customer service crush to operate in reverse, with the lust flowing not from customer to employee but from employee to customer. Rich, the EMS shopper, found himself on the receiving end of a customer service crush from a 70-something cashier at the place where he buys his lunch. “She’s a short, cranky little old lady,” Rich says. “But she rang me up every day, so I always tried to be nice and chatty. One day I go in there and she’s like, ‘Do you know how to dance?’ I don’t know why, but I kind of knew what was coming, and I said, ‘Me? No, I’ve got two left feet.’ She said, ‘Cause I’ve got a Sadie Hawkins dance next Friday and my regular date has bowed out.’”

In part because of the 50-year age difference between them, Rich was, he says, shocked and a bit unsettled — though not enough to start buying his lunch elsewhere. “The guys I work with said, ‘You shouldn’t be so friendly anymore.’ But I was very flattered. It’s always nice to be asked out no matter who it is.”

Believe it or not, some customer service crushes do end happily ever after. Just ask Susie Gelbron, a 31-year-old letterpress printer in San Francisco. In February 1998 she was outside a Patagonia store with a friend when she saw a cute guy she’d noticed walking several blocks earlier. When Susie pointed out the guy, her friend recognized him as Steve, a college classmate. It turned out that Steve worked at Patagonia, and Susie and her friend followed him inside.

“I was really nervous because right away I thought, This guy seems great,” Susie says. “He went into the back and my friend was like, ‘Pull yourself together. You’ve got broccoli in your teeth! You’re a mess!’ She was handing me lipstick and trying to fix my hair.”

Unfazed by this Bridget Jonesian introduction, Susie called the store several times over the following week to ascertain when Steve would next be working — and when she figured it out, she went in and asked if he’d like to have lunch. Steve now jokes about how Susie “stalked” him at the store, but apparently it worked: They’ve been a couple for six years.

Though it was, of course, Steve himself who attracted Susie, his place of employment didn’t hurt. “My idea then of getting dressed to go to a bar was cute jeans and a little Patagonia vest,” Susie remembers. “I thought black Patagonia [jackets] were the bridge to dressing more like an adult.” In fact, the merchandise played a key role in their early courtship: Susie wore Patagonia shorts on their first date (“I didn’t want to be too dressed up”) and for her birthday — 12 days after they first went out — Steve gave her a fleece jacket.

In short, it was a match made in customer service heaven. As Susie says now, “My mom joked that she couldn’t believe I found a boyfriend and a discount.”