Going to agree with Thuriya here.
When I went in I had 3 requests:
1.) Do not change the length of the top hair.
2.) Shorten the sides to a 4.
3.) Thin the top.
In the process of cutting the sides, my hair went from down to my chin to eye level. As justification the goal was to make it so that it would be even. With the original length it would have been possible to just slick the hair back until the sides grew back in, but the top length was cut by 3 inches. I had spent the first half of the year growing it to this length, because most hair stylists tend to cut it short.
In terms of how to avoid the scenario it would have been easy to just clip the top hair out of the way so that you can trim the sides with the hair clipper, not move the hair clipper up the side of the head with the top hair still hanging there.
Oh and not to mention the lack of privacy. I need to give my phone number for the records so I can get a hair cut? Not true. For sake of ease? Hardly. I refused 3 times, but each time they kept pestering me for it.