In the perfect world mechanics are honest and their prices are reasonable, they never replace parts that were not broken and they never charge you for something that is an easy fix.
But in reality, they will rip you off as soon as you give them a chance.
The best example we have heard is a Porsche coming in a shop for a broken cruise control.
The mechanic charged him around $2,000 for replacing the cruise control computer, after which the cruise control started working again.
The catch was, that some cars automatically block the use of the cruise control feature if a brake light is broken, and the mechanic knew this but did not tell the customer.
So, he ended up changed a $2 lightbulb and charging the guy $2,000.

So to prevent situations like this, watch the video and hear what this guy has to say.