At the store I work at we have a driver that acts just like Billy Bob Thornton's character in Slingblade. He's not mechanically inclined, he's blown up every car he's owned... you get the picture.
When ever he is helping a customer by looking up parts, I make sure to drift over to make sure things go right.
Another guy is supposed to be the 'parts pro', whatever that is supposed to mean. He's another one that is only about 3 steps above the driver in intelligence. This moron helped the driver 'fix' his car. The driver had said his car was losing coolant and was overheating. The 'parts pro' says, you have a bad head gasket, and dumped 3/4 of a bottle of stop leak in it. Well, needless to say, the engine went boom. The 'pro' did no troubleshooting, didn't pressure check the system looking for leaks, didn't pressure check the cap (the cause of 90% of missing coolant), he just dumped in a PARTIAL bottle of stop leak. (I really wish we didn't sell that sh!t... all it does is screw up engines.) I heard that the driver had blown up his car and I asked what happened. Then I asked the driver if he had seen any smoke from the tail pipe, smelled the sweet smell of burning antifreeze, etc. No to all questions. According to the 'pro', he owns some 12 second Pontiac Firebird that he drag races, but I can't find a video of him racing anywhere. So I call 'bs' on his whole 'racing experience'.