Hair cutting salons' sales pitches

Too many are the salons I've been to where the barber makes desperate attempts to cross-sell. The customer ends up cringing as we are stuck to the seat and tired repeating "no".
It also makes the customer conscious as many a time the barber makes negative comments on the customers hair in order to sell other services.
For example saying that you have lots of grey hair or it's full of dandruff etc.
Effectively the bad memory means the customer does not go back to the salon.
This is something salon owners should know. They should train their barbers to ask one question: " Would you like any other services like a hair colour or shampoo". If the customer says "no", stop bothering him/her anymore!