If you looking to buy one there is a real easy test......

Look at the back side of the supercharger pulley. If there are any dents or creases, the car has been modded and put back to stock.

You can also look under the car and see if it still has a U-Bend or performance mufflers.

Bottom line is you have to take it for a test drive and I would take it to a trusted mechanic and have them do a thorough check before buying.