I usually just do what Lunalafey does... Ask what the person is really like underneath any masks they may have put on in public and to me, and draw 5 cards. I also find it useful to find out what they WANT me to see them as, y'know, what masks they put on to me.
I'm not being nosey, and I don't think this is ethically wrong, as lots of people would say, cuz I would try an dfind these things out anyway in normal everyday life. The cards are just another way of doing it, and I reckon I'm entitled to know if they're taking me for a ride or being deceptive, so I don't get hurt!
It also is helpful when I become friends with somebody who is not entirely mentally stable, or who has some serious isues. Finding out what they're really like underneath all those masks helps me understand them more and work out how best I can help them.
"Pistis Sophia: the Goddess Tarot" (forthcoming) http://pistissophiatarot.com
"Tarot 101: Mastering the Art of Reading the Cards", by Kim Huggens, released by Llewellyn Worldwide, 2010.
"Sol Invictus: the God Tarot", Schiffer Books, 2007.