While it's true that a car in regular use would likely have most issues ironed out, a proper pre-sale inspection and extended road test by the dealer should have picked up most, if not all, of these faults.
I totally agree Mike.
I guess it would depend if it was a car owned by the dealer or one on a commission sale as some owners are a bit precious about racking up even more than a few miles on their car if its on sale or return.