I think some people take a simple comment or gesture too far. For me I find it quite a laugh when a male passenger that would obviously have no chance with me makes a remark or like on the Moscow the other day one of them kissed my hand and took a photo of me as he left the aircraft, but I know of some girls who would make it into such a big deal. I think there's a line. If it's a simple kiss on the hand or even one pinch on the bum or something it's ok in my book, but if throughout the whole flight they kept doing it, kept making horrible comments etc. then I'd say that could possibly turn into harrassment, unless it was a real cutie, then hey, be my guest!
(Only kidding!)