I know what you mean, which is why I will remove and refit my own wheels when I get the tyres changed. The first (and only) time a tyre fitter did the whole job - on my old XJ900, they allowed a pile of dirt to get into the drive gears. I was lucky enough to pull the wheel a few days later while doing the brakes and found it - it would have destroyed the crownwheel and pinion if I hadn't caught it.
When I rang them about it, they said the dirt had probably blown in there while the wheel was off and they were fitting a tyre, and nothing else - needless to say I avoid that place now...

