How can you tell if someone is out of your league?
ALWAYS look at it as though they are out of YOUR league . That way there won't be that question, by you OR them.
Most of the time it's pretty obvious when they are but to answer your question sometimes they have alot of friends and people look up to them. This is really superficial but looks are part of it also.
Tip: When you're attracted to someone you think is too good for you, that's the one to go after.