Wow. The fire starters in this thread mostly exemplify the kind of customers I try to avoid whenever possible.
Fred and Rick nailed it. Mechanics are the lightening rods for blame of seemingly every single problem a car will have during it's service life. I wish some manufacturer's, or SAE engineers would take over explaining these part failures to the cars' owners so I don't have to. Their designs weren't my idea anyway.
I just shed a customer that threatened a BBB complaint because his GX470's rear brakes only lasted 30k miles. The 22' Malibu Wakesetter they tow is not a contributing factor, according to them. I gave them parts from Lexus at cost, and all the labor for free just so I could escape the situation relatively unscathed. Even though nothing I could have done would have made the brakes last any longer, short of removing their trailer hitch, I had to take a hit, do free work, and listen to some sht talk to protect my business from this client's quest for supposed restitution.