There is power in it on both sides of this response-for the person (likely a business owner/CEO) who is able to make the decision and communicate it, and for the person (likely the sales professional) who now safely knows they are ‘barking up the wrong tree’.
There are two NO’s for the business owner; 1) I’m not interested in providing services/products to you (the most empowering) and 2) I’m not interested in what you’re selling.
The latter response allows the salesperson trying to sell you, to move on. The former means you are in a position to actually turn down business – and that likely indicates you have hit a stride towards true growth, which allows you to be selective in who you work with.
The NO for the salesperson who has been knocking at your door, leaving cards and phone or email messages, is simply respectful and professional. If you’re not interested, have the decency to give them the NO. Let the salesperson move on to others who might utilize the products or services they are selling, and stop them from agitating you!
Whether the NO is being given by you, or to you, it is an opportunity for all involved. The top decision-maker can create a client/customer list that they are inspired to work with, and the salesperson can choose to re-evaluate and refine their approach, and be free to look for new prospects.
Moral of the story, just give the NO and everyone moves on to greener pastures.