Its been there a fair while but given that the economy is fecked I'm not surprised at anything like that hanging around in honesty. The fact that its bright Yellow will also restrict the number of purchasers.
This whole business about 'dodgy dealers'...whilst I appreciate there are some real sharks out there I doubt there are dealers who actually go out just to find gash cars. The difference is the service really - your just as likely to find a dog Zed at a Nissan garage as you are in Joe Bloggs Car Emporium.
Mostyn Garage is your typical small enterprise who've got a decent sized forecourt, usually have a fairly decent selection of sports cars and probably got a couple of mechs working in the garage at the back. He prob wont budge on price as its just been reduced so he's sticking to his guns.
Unless they've got a fairly decent money laundering operation on the go I'd hazard a guess they're quite successful given the types of cars they sell (having a Ferrari and various Porsches on the forecourt is no small amount of money to tie up in stock).
I'd just do what you would normally do when buying a car (whomever you get it from).........check it thoroughly and make sure your happy with it. If not walk.
I'm literally down the road from it if you want me to take a closer peek?
EDIT - Also you'll be surprised just how good you can get the leather looking with a bit of Gliptone cleaner and conditioner. Might not even need a repair.