I never compliment women's looks, attractiveness, lack of or anything else of that nature at work. It is not the place to do that. I am not perceived as an ******* for not commenting on their looks, maybe in other ways though.
Likewise I have never commented on men's looks that I work with and never had anyone get upset.
I have commented about something in a non sexual or looks way. For example I have told a co-worker man and women that their new shoes are cool.
I think the line is pretty easy to see and not cross and have never had an issue with it. Work is never a place for hitting on people in general and you should never sexualize or hit on people if you are their boss or superior in a work place.
I think the majority of women dont want to be hit on at work or have people people comment on their personal appearance. They are not dressing that way for you.
Yes, your wife/girlfriend/friend/family member is different and might expect you to comment and get offended if you dont, that is very different.