I would never trust an auction. An auction place is the worst as you can't test drive or have much knowledge about what you are getting before hand. At least a classified you can call up the person and ask if they have car history, past problems, have a carfax report on their car for you and do general research online about common problems for that year model. It still isn't as safe as a dealership but a used dealership can be just as bad if you are not careful.