If i owned a beauty salon, what are the DISADVANTAGES of not retailing to the clients?

If i owned a beauty salon, what are the DISADVANTAGES of not retailing products to the clients?please help thanks also what are the signals a client gives off that suggests they are going to buy the product if you have been retailing to them?taIf i owned a beauty salon, what are the DISADVANTAGES of not retailing to the clients?
Well, as a customer's point of view and also I understand a little about business, the disadvantage would be less revenue that you could create from your business. From what I understand, having a higher revenue can show signs of a strong business, especially when it comes to recruiting new employees. When it comes to a customer buying a product, you could probably tell that you could sell it if someone comes in who is slighty confused what they want done to their hair, and you explain to them what you are using and how you're using it when styling the hair, and if they like the style they will probably want to buy it so they can do it at home. I know this because my mom has done it several times, cause she loves the ';leaving the salon'; look and wants those products. Plus, it's convenient to them, so they don't have to go to a beauty salon store and find it. It's easier for them to just buy it there. Hope it helps, not too experienced, but I'm trying!