It depends on the context, situation, and the guy. I'm a guy, so personally if I'm looking at a woman, it's usually because I am attracted physically. It's not something I can control. If I am caught looking, and quickly turn away, that means I am really attracted to the woman.
It may very well mean that a drugged guy is looking at you
That he wants to "get to know you better."
They have the same interests
he is starstruck
Nothing. He is a nice guy.
it means she likes him
Not necessarily.
He is simply a guy! guys do that unfortunately!!
If a guy looks at a girl when she is not looking, that does not always neccessarily mean he likes you! Hope this helps! =)
...it means that the guy you like, likes you!
He is flirting with you and probably has a crush on you.
it means he likes you