All the skid pad cars I have seen wouldn't look out of place in a stock car race 
I found an ex Thames Valley 3.2 Estate in white in a local scrap yard several years ago. It was obviously straight off skid pan duties, as it was fitted with large rubber mudflaps that went upto waist line height on the vehicle, and was heavily caked with dried oil underneath. It was damaged on its fns corner, which eas probably ehy it had been scrapped. It still had self levelling suspension fitted. All the underside components were totally rust free, so needless to say it was quickly stripped of its front suspension, wishbone, rear shocks and springs - all of which were genuine GM and protected by the oil coating. It appeared to have been previously a traffic patrol vehicle judging from the equipment holes in the trim.
Lancashire Police have not had a skid pan for years (perhaps down to the health and safety?), but when they did, operational cars were used at the end of their service prior to subsequent disposal. I have some great photos of Triumph 2000's razzing round Lancashires skid pan in the late 70's / early 80's....
Driver training cars generally don't end up looking much better.
Lancashire Police Driving School used to be one of the best in the UK, until the cuts started and they moved out of their wonderful Police Motor School into basically an office block and prefab garages.
In the old Motor School premises, the cars were washed and leathered off everyday after the 'run' by the students, and they were immaculate without the normal abuse that section or to a lesser extent traffic cars were put through. The interior trim was always good as the drivers weren't carrying handcuffs, batons that caused untold damage to the interior trim getting in and out of the vehicles. They were 'driven', but not abused, so were generally a decent buy second hand. And the majority weren't white either.
Other Police Forces used to send Officers to Lancashire for Driver Training, so they had an example to set with their vehicle fleet.
The good old days.......although they only ever had one Omega, a white 3.2 auto....