If it hasn't been abused, then its likely a great car. Of course, even if it has been abused doesn't mean it's automatically a bad car to buy. The fox mustangs are by and large extremely easy to work on (especially compared to a contour) and really easy to modify to your personal tastes of performance (both straight line, and corner carving, despite popular opinion).
Probably the most telling way of checking if a particular car has been abused or not, is check the torque boxes. Basically the sheet metal area that makes up the body-side mount of the rear lower control arms. Abused cars tend to have cracks, etc. around this area. Note that even if the area is cracked up, a good body or chassis shop can replace or reinforce this area fairly easily, so use it as a tool to get the price down.
