These stories are easy to laugh about, yet I have only to walk into a hardware store to realize that there are a great many things which are obvious to everyone else that are a complete mystery to me. Many photographers are disappointed with their pictures when the get them back from the lab. They automatically blame themselves for prints that are too light, too dark, off color or scratched. Even some experienced photographers believe that the first set of prints are somehow ideal in terms of overall quality. The truth is that it is quite possible, even likely, that they are not.
Printing is an inexact art.
If your lab allows you to examine your prints before paying for them, then by all means do so. Most machine-printed photos have the settings printed on the back and can easily be corrected. The only way to really tell who's at fault for a bad photo is to examine that negative, THAT'S the original. Film is a permanent record. Slide films will last longer.