Rule #1!: No title = NO SALE! When buying from a private seller, if the seller can not show you a valid, clear title with HIS NAME in the owner's space, DO NOT BUY THE CAR!
Rule #2: Always have a used car inspected by a mechanic who you trust before making an offer to buy it.
Rule #3: If you're buying from a dealer, GET IT IN WRITING! Doesn't matter what the salesman tells you. If it's not on paper, it never happened!
Rule #4: Once you buy a used car, IT'S YOUR CAR AND YOUR PROBLEM! You can't give it back just because you don't like it or it smells funny or some other stupid excuse. Once you sign the title, you own the car. DEAL WITH IT!