I am as bad as anyone so I ask them not to wash, I also park it well away from other cars and ask them to do the same after the service, this stood me well on a three series once as we did the usual walk around and do not clean but I also requested not to park in between cars, anyway after work i went to pick it up and to my horror it was parked right between cars and had a dent and paint chip on the contour line of the rear door...I really was not happy but they did agree it was their fault and after a botched first attempt they did get the second right with a full side respray.
I did also prep my black gtI pp myself but I am not sure I would do it again as I had five paint defects, two dings one bumper bulge as if it had been pushed on to an unscrewed screw and two tiny flecks under the paint, I had my pdr guy around next day and he took one of the dents out a ten pence size in the bonnet...actually be said it was not a dent but some sort of recess in the paint perfectly round, I asked if I should return to the garage and he said no need...twenty mins later it was completely perfect as for the other one it was so small i only found it a week later on the side of the roof above the rear door, pdr guy could not get any tools to it as it had a sub frame underneath.
I actually sold the car 11 months on and have just got a white gti pp same millage 6 months older for the same money..no 19" wheels though, it does have lots of swirl marks though so I have got some work cut out but it should polish up nicely ...just a shame after buying the first gti new and putting all the prep work in deep down i knew I had made a mistake or just been unlucky.