I have found all my cars from craigslist, and sold some with no problem.
There is a list of questions I ask but before anything I check the mileage on kbb to get a value based on the options offered with the car, if some options don't work, I take that off the value.
If the car is reasonably priced compared to it's KBB value then I move forwards with the questions and then go check it out and see if they have a title or not.
In the end I do a CarFax to verify mileage. Only if everything checks out do I buy a car, I refuse to buy cars with a prior accident history, even if it was suppose to be a scratch.
Compared to the KBB value, I have always bought my cars 500-1000 dollars lower, you just have to find a reasonable seller and all the things your looking for.
Right now I'm in the market for a 2001-2002 Toyota Corolla S, preferably Red in color with all the working options that came with the S model. There is one in Chicago at the moment that is reasonably priced.