Stuff like this is why I always look down into the oil filler cap if possible. I've come across countless used cars that are sludged to hell inside, I avoid them like the plaeg even if it's just heavy varnish. You just gotta look over and listen very closely to everything you can think of. Never take a used car dealer's word for it that the car your interested in has been properly inspected. Most will do pre-sale oil change and that's it! They aren't going to take the time or money to check and clean an already screwed up engine from sludge.
I had a white base auto 2013 v6 mustang
, bought brand new June 2013, and then recently found a GHIT 2013 premium manual v6 w/performance package with the same miles my white car had, plus just about every mod I originally wanted. Fell in love with it instantly.
It appeared that the previous owner took really care of it like I did with the white stang. Even a peek inside the oil filler showed the engine was just as clean. So far a month into the purchase, it's been a great car.