Venson,
I have been trained to repair vacuum cleaners. I was started at age 9 and when the company trainer came in from the company to train me, at age 37, as branch manager, I was teaching him in the end. I work with electrical motors,but I don't have to be an electrician to do it. An electrician is licensed and trained to put in electrical systems in a home. If I wired a house and made an error I would be sued and it would cost me big time. An electrician not trained to do vacuum cleaner repair would not make it in this service end of the industry. Several electricians told their wives they could fix their cleaner in my area and ended up seeing me to fix the cleaner. Talk of a license has been around for some time now but it was determined at least in my area that the cost to have a staff to test and train would cost to much.
In a big box store no qualified people that truly know vacuums are hired. They( the sales people ) are not trained to know vacuums but to use their sales skill to make their commision. The higher price cleaner the more they make. I speak of Best Buy, Sears, ,H.H.Gregg and others.
Ther are, as you say ,people that don't know what they are doing and end up hurting the good vacuum repairman's rep but it doesn't last long because customers pass the word around about how good you are.
Procare