The problem is, if you are complimenting a woman and you don't know them how can you tell where the boundaries are?
Some women will say thanks, some will say creep, some will automatically think you are trying to pick them up.
What makes women get nervous when a guy says something complimentary?
An instance at my work recently is a perfect example of this. One of the guys in the sales office lives with his male partner. We have a single woman here that wears quite short skirts and often has low cut tops. She does have a good figure and legs and likes to show them off. She recently came back from holidaying abroad and he said what a lot of the guys were thinking which was 'god you're lovely and brown, is it an all over tan?'
We waited for the fireworks and none came ~ she just smiled and said 'nearly, but not quite'. The point is, a couple of weeks before that, one of the guys said to her quite innocently (he's got a fab girlfriend so I'm sure there wasn't anything in it) your perfume smells great. You would have thought she'd be pleased, after all isn't that why she wears it? Instead she made a scene right in the middle of the office and told him not to be so personal and if he made any more comments she was going to report him to the manager. WTF? He was stunned and so were the rest of us.
We've always made a point of being polite and courteous here, but now we are wary about what we say.