I never trusted them for a second, but in Britain, they ran a scam where a laptop with a loose memory chip was taken to 6 shops. 5 of them tried to SCAM the owner AND they pried into personal files. 5 of 6, Thats about how I had it figured. They're not ALL crooks, but at that rate, CLOSE ENOUGH.
Same applies to these discount tyre and exhaust centers. Usually they find that a car brought in for something else also has a faulty shock absorber. They take it off, clean it, replace it and then charge for a new part.