Check the paint outside in bright sun or inside in bright flourescent lights for match.
I have had, and read about PPI's that left out plenty! Look through the car yourself for telltale signs of repairs that have not been made that were needed. Interior finish and engine cleanliness usually indicate something about the seller and the car.
Check the front for leaks of all fluids as well as the transaxle.
As Porsche dealers go, most have never worked on a 968, and will not give you a real picture of what is wrong. My local dealer reported bad running lights because they did not know how to turn them on,,,does not inspire confidence.
My advice is to get the PPI done at a shop that works on and knows 968's. It will still take about $5k in the first year to get her running and repaired to tip top shape. These are WONDERFUL cars, but costly. Caveat Emptor.
Good luck, I hope that she turns out to be a winner.
P.S. ask for service records, the more you can get usually indicates that she has been maintained well.
