As a women in my 30's...I would say in todays word (where there are some odd people around) I usually do not compliment men that I do not know. It just feels safer somehow if you give a another woman a compliment, or give a much older man or younger (like teenage boy) a compliment. You have to understand sometimes that women (that are strangers) are not necessarily shy but rather cautious about stuff like that on a daily basis...and unfortunately for the majority of totally normal guys out there, there are those few that are always around mixed in with the general public that give us good reason to be. Maybe that sounds somewhat paranoid but when dealing with total strangers, it is rather true when you are a woman and a type of behavior that you somewhat adapt to.