it's a bit like car garages and mechanics though isn't it, you hear horror stories about some, so others get tarred with same brush.
I know next to nothing about cars, so when I take my car for an MOT, and it passes or fails, i pretty much have to believe them, I guess I go to a good garage as they haven't found much wrong over last few years, and things they did were normal wear and tear/me not looking after car properly
Ppl moan about chains like Kwik Fit, but the couple of times I've used them, they've been fine, I'm sure there are ppl who have been to a kwik Fit after a puncture, and have been told they need 5 new tyres, an exhaust, and other things.