If dating someone how can you tell if someone is married or not?

Usually a ring on the finger next to the pinkie of his left hand is a good sign; or any white indented band of skin there where a ring would normally be. If he doesn't wear a ring, and doesn't say he's married, it's almost impossible to tell. Some hints could be if he never brings you to his place, or something like that. if they have a ring on their marage finger the are married.