When they install a new exhaust system and put the catalytic converter on upside down. Then proceed to try and tell you how it's better that way because now that shield is on the bottom side to protect it from stones etc.( ya know, the heat shield that is there to keep the cc from starting your car on fire).
You go in for 3 new tires, and tell them to use the spare under the Truck as the 4th. They can't get the cable-ma-doodle thingy that holds the spare, down, so they proceed to cut the cable, thus, releasing the tire. You pick up the Suburban at the shop and THEY DON'T TELL YOU. You drive home, and find a spare tire in your back hatch. You call back and ask WHAT THE $%^& IS GOING ON. They apologize for not telling you, and say they couldn't get the tire off so they cut your cable. You then find out that a new spare tire "thingy" from GM is a few hundred bucks, so you just proceed to ride around with an enormous spare in your rear cargo area.
When you tell the guy you want the white letters turned in on your 4 new tires, and you hang out a Super Shoe for an hour and come back and all the white letters are out. When the boss told this guy he had to change them he said words that even my 10 year old nephew wouldn't use. true story