I think the fact of the matter is this:

1st - Like RJ stated, people do bring problems they created to performance shops looking for the almighty cure.

2nd - It's hard to say "customers are always right". Think about what some people could do just in spite to rip a business off.

3rd - If someone complained in a level headed manner and the shops blows a person off, they have every right to tell the world. There is no better way to advertise than word of mouth, whether it's good or bad.

4th - A shop will always have more negitives told about them than positive... it's just the way the world turns. 2 out of 5 people have a bad experience, the 3 that had good experience usually dont commend the shop.