The first time I went through I didn't find Croc that attractive, but I have since he's made a comeback into the story. I don't know too much of a difference (outfit aside) from his appearance in Alabasta and now except Oda style obviously changed a bit, but they're pretty consistent.
He would be the biggest pimp in the series if he wanted to be, that's for sure XD He's one of the few characters that's canonly been swooned over (if i remember correctly XD).
I think his scar is pretty hot, it adds to the badass factor. I'll exclude all the reasons he's hot for it would be a super long post XD