Location, Location, Location, are the three most important considerations in Real Estate.
Condition, Condition, Condition, are the three most important considerations in Used Cars.
I agree with @VDCdriver's advice that maintenance/condition is more important than make/model when it comes to used cars, almost every time.
The maintenance is what influences condition and to determine condition, maintenance records are helpful and a careful inspection is essential.
I've bought lots of used cars, the last one off Craig's List (the little beauty in the photo at left)! I've always done my own inspection and fortunately have never gotten a bad deal, yet.
I've probably been somewhat lucky, but if one doesn't know what they're looking at then they definitely need a professional inspection.