It is humorous when one of the first words we learn to say becomes one of the most fearful words to express. “No”. The reason for “no” to be the most fearful word comes from the want of not wanting to be misunderstood. We do not want to appear to be aggressive nor rude. Neither do we want to ‘go with the flow’ and say alright and have no opinion and seem to have no thought with or against any matter.
In the sales discussions, it is quite important to express, on both ends, the importance of saying no. As the salesperson; a good way to gain trust and present an acceptable front is to verbally say, “feel free to say no if you don’t agree or if you are confused on any matter” This internally can relax the client and, they may, in turn, listen to you with open ears.
Love the comic! I myself often have trouble saying no for the very reasons you listed. It is so important to understand the culture surrounding your buyers to understand the concept of manners that leads to people not saying no.