Honestly, I'd rather someone like that back off because he thinks I'm another guy's property than persisting and trying to get me to cheat on my boyfriend (who may or may not actually exist at the time). Both are icky and sexist. The second is just...more arrogant to me. Especially when it comes with promises of how much BETTER Sleazy Jerk will be in bed, etc. Or how he'll buy stuff and has a nice car.

Ideally, I'd prefer people to just not be sleazy jerks, but backing off when told "I have a boyfriend" is the lesser of two annoyances in my opinion.

I'm kind of shocked that some guy was being skeezy while he was at work and while you were a customer. Although the biggest OMGWTF were you thinking incident I've ever heard of was this guy who my boss interviewed that wouldn't stop staring at her boobs during the interview. Suffice to say, he was not hired, nor was he called in for a second interview.