Why do men do the same thing? I personally prefer to observe a guy when they don't know I'm watching. Guys tend to act differently if they know you're looking at them. Does that sound creepy? Haha. I don't exactly know in what context you're talking about, but I just like to watch the way some people act when they aren't worried about impressing people.
I look at guys when they're not looking because I don't think I'm pretty enough to look. So it's a self confidence thing. I also don't want them to think I'm weird because I'm looking at them. So embarrassment is also a factor. :x