I've often complemented strangers or colleagues or people I know on their hair, nothing creepy or sleazy, just "great hair/very beautiful /impressive etc." Almost every time it results in a smile and casual "thank you", I've never had negative reactions. Some then start to talk about their hair, which is enjoyable. And on rare and delightful occasions they offer you to touch it themselves. But I never dared to ask that. I am happily married to a woman with beautiful hair and it would feel like betrayal playing with the hair of other women. And my wife seriously wouldn't like it if I did... One advice though : don't talk about the fragrance, even if you notice how good the hair smells, most people find that extremely creepy...