Some Mechanics Don't Know Jack

I recently had a problem with my car. The engine was riding quite rough and I took the safe route and had it towed to my mechanic. He determined that I had a bad spark plug wire and put on a new set of wires and said everything was now good. I took it back two days later because the engine was loud and uneven to me, since I've driven it since it was new in 1997. He told me there was nothing they could find wrong. Since it was there I had them change the rocker arm cover gasket since it was leaky. Last Friday I went to change my spark plugs because that's the only thing left I could determine could be wrong with the engine, before I started looking for a new car. When I backed the car up to get at the plugs I noticed a small puddle of oil on the garage floor. I got out my hydraulic car lift and saw that the engine was wet with oil. When they changed the gasket they cleaned the engine so this was fresh oil. First things first, so I pulled the wires to get at the plugs. The two middle wires were nice and dry and the two outer wires were soaked in oil. I got out my ratchet and put three turns on each of the outside cover bolts, the middle ones were fine. Now I need to replace the gasket again because it's oil soaked again. I replaced the plugs, cleaned the wire chambers and the car now sounds back to normal. Now it's time to tell my mechanic, who obviously doesn't know jack, that he's replacing the new one for free now since the repair was not done correctly the first time.