im pretty sure you're on about my thread a few weeks ago, if not my mistake
like ams said you get the bad and the good on both sides.
personally iv always bought my cars from dealers. the celica i got came with a free 3 month warranty which covers engine, gearbox and suspension.
my Pug i got before the celica came with a months warranty, the driveshaft went and i returned to the dealer and he fixed it within a week. it wasn't on his priority as he already got the sale but if i got it privately the repairs would come outta my pocket.
my older bro bought his MR2 from a private seller and the head gasket went, so he paid for it. then he bought an audi A3 and the turbo went on it..
personaly i will always get my cars from a dealer, from my brothers experience im not guna go private