A good salesman will get you to take a bad or mediocre deal while at the same time convincing you you've gotten a great deal. Always question "facts" thrown out

A good salesman will get you to take a bad or mediocre deal while at the same time convincing you you've gotten a great deal. Always question "facts" thrown out by someone trying to sell you something. "instead of doing a price cut, it may be worth explaining why your product is worth more." This is news?