Flip side: Then there are the customers who know something is wrong and won't let the wrench fix it.....as in:
Last week, Bubba Luke did a brake job on an RV--total bitch of a job. He pointed out that the exhaust had holes all up and down it--not good. Customer said, nah, it's fine, don't fix it. (All you have to do is look under the vehicle to see holes in the exhaust, no big secret here). Bubba didn't fix it, RV drove away, and 30 miles from the shop the heat from the exhaust burned a hole in the air bags that give the suspension ride to the rear end of the RV.

Customer called screaming, and blamed it on Luke. He destroyed the suspension system!! At least the Boss stood behind Luke because Boss saw the exhaust pipe as soon as the RV came into the shop. Customer went elsewhere for his exhaust job. That's OK, we don't need assholes, shop has plenty of good customers.