Cambelt will have been due on age. 5 years i think was the limit, so ties in with that. Take a magnet and try areas for filler? If it doesn't want to grab the metal continually then walk away. Other option is view and then AA inspect it...do the cheap version as it covers most basics...
Being black, I am willing to bet that no matter the expertise as a panel beater, the colour will be slightly off if its been sprayed. Look for signs inside the boot, and underneath at the rear. Thing is though, a lot of people round my way have colour coded that lower valance as it just a big bubble of plastic on the rear otherwise, as its not got any styling like even the standard GTI's.