I wouldn't say you're being a real jerk. Sometimes I think that to myself, and have to adjust.
I wouldn't necessarily agree with the hotter the woman is, the better she responds. It's a bit about their confidence level. For example, I know a girl whose confidence level isn't the greatest, even though she's about an 8. I have to be "nicer" to her to get her to respond... usually I'll do this by cracking a joke on her, getting her to make that "OMG! PJ, I can't believe you just said that!" face, then I'll crack a joke about myself, which usually gets her laughing hysterically. Another girl I know, she's a 7, and her confidence level is very very high. I called her up today (after a bit of phone tag, her calling me, me not answering, calling her back, her not answering, her calling me back, etc.), and she immediately answers the phone "HEY! What's up punk ass!? *laugh*" I don't have to resort to picking on myself with her to get her to laugh.
So are you being a jerk? No, you're being yourself. But the tip I have to give goes like this: If she seems to become intimidated and bothered by your comments, simply throw in a comment to bring yourself down to her level (in HER eyes.) She'll lose the feelings of intimidation almost immediately. If she responds negatively, and throws the comment right back at you as a means to get back, then ditch her, because she's a bytch anyways, and just looking for someone to boost her ego.
As for being in the work place, it's usually a more "professional" atmosphere. A lot of the ****y and funny routines will get you in trouble. Basically, get to know your customers before you start acting like a goof ball.