Having been a bike mechanic myself, I can tell that there are three kinds of bike mechanics. The first are young people who are mechanically-inclined, and want to become professional mechanics. These younger people have little experience, but luckily, bike maintenance does not require very much. The second kind are somewhat mechanically-inclined, but not enough to move up to automotive or other work, which pays far higher. These guys are usually pretty good at what they do, and they seldom get complaints. The third kind are shop owners who are also mechanics. These guys can be highly skilled, but also highly inclined to get their customers to pay for unnecessary work. The bike business has always been tough, and bending the truth to help fund the overhead is a necessary evil to these guys.