sales rep

I haven't experienced the type of sales represntative job in my life. Of course, all people working at a company work to earn money, and they are in the sales more or less. However, the person like of me who don't have the experience of the sales rep and the person who has it is not the same when they tell something at the same situation. I think the sales rep wants the logical conclusion even though it is not the fact. It is difficult to explain the reason of the system trouble to the customer keeping the marketing strategy.