How would you react if you saw a woman being treated like that? Would you intervene? Are there extenuating circumstances like if the guy is drunk?
I'd definitely get right in there, all 5' 2" of me, and tell the jerk to leave her alone very loudly (that way there'd be alot of eyes and hopefully some surrounding "muscle" that could back me up). I could care less if he's drunk or not. The person still needs to be told he's gone too far. If they were drunk then hopefully when they get sober they'd be so shamed about it that they'd be more attentive next time.
What about a guy in drag: Would it be appropriate conduct towards him? Is it a little fun, maybe?
Bear with me now. What about a guy in a kilt? Is he asking for it?
Oh this brought back to mind my visit to a Montreal club called "Soma" (spelling?). All of the guys in drag that we ran into in there, were quite liberal with the innuendo but it was all done tongue in cheek. Its common decency and respect to that person's dignity to keep any sexual innuendo or jesting to a level that's a bit more reserved than theirs....so that you definitely don't cross their boundary (even if they're quite free about it) and you can moderate their level as well to some extent.
A guy in a kilt is not ipso facto asking for it. They shouldn't have to bear that question about whats underneath. But really I don't see much harm in people asking it to a guy out of playfulness or jest. It certainly shouldn't go beyond that though and if its obviously too sexual then its become harrassment.
Does his silence on the subject give an open license to be abused?
That should be any right-headed person's cue to cut it out, respect the person's choice to silence and go elsewhere with the conversation.