Just bought a 92 300E Sportline, one owner, 189k miles. This guy had cash -- spent $13,000 in the last few years, on just the usual, at the Mercedes dealer. They did a valve job and dented the fenders. Replaced the belt and tensioner pulley without noticing the water pump was worn out. Broke the rubber grommets which hold the air cleaner to the block, then broke the air cleaner itself. Replaced the drivers door window mechanism and tore the door pull. $186 dollar oil changes. 5 flex discs (you think maybe the driveshaft itself is out of balance?). Nah. Flex disc number six. Didn't notice the massive oil build up on the engine until it looked like a 73 Vega, then charged $100 to steam clean it. All the while leaving the source of the leak, a hard as a rock power steering pump cover gasket. Replaced the fuel distributor with a junkyard unit because the car had a bad idle. Check the fuel injectors or cold start valve? Nope, hey, those things never go bad. Unless they did. Welded on a new rear muffler -- $900 unit -- crooked. Etc.

Either inept, or crooks, probably in between somewhere.