If I may break into this dialogue....
...a teacher? .....a policeman? These are figures of authority....what about a medical person.....like a doctor?

Hmmm, I know I think I'll market myself as a doctor

....even better Doctor Carpet

Actually guys, there's a serious bit to this. AS you know I worked in banking and selling the bank's services was (regrettably) a big part of the job. Without sounding too big headed I was extremely good at it. Somebody told me I was probably the best in Stockport. But the bank didn't value it so instead my clients in carpet cleaning benefit instead.

One thing I did learn was a very simple trick. And that is to say of something "I recommend it".
If you are selling, as in this thread, protector, then if you come across as a professional then you are in a position of authority. AS such if you then recommend something chances are your customer will accept what you say as gospel. Now I know this relationship between cc and client could be abused and that is why "less is more" and why I will dissuade some customers from wasting their money on it but in other cases be quite forceful in pushing it. For some reason clients will often subliminally be able to pick up on this.
But at the end of the day recommending something works best when it appears to the client that you are not desperate for the sale and that it bothers you not which way the client decides.