No it really doesn't. If you arent close friends with a coworker you treat them professionally no matter their sex. If you compliment all your coworkers male and female on their physical appearance nobody is going to bat an eye. If you only compliment those of the opposite sex or a specific person then it can validly be considered sexually motivated and harrassment. If youre friends with someone then you would know if they would find it as harrassment, if you arent sure then you either arent close friends or default to dont do it. Youre at work to work, not make friends. That just tends to be a side benefit.