The marvel of a good magic trick is that the “how” is hidden from us. We do not fall for bad magic tricks, mainly because the sleight is obvious.
Good sales is hidden as well. The salesperson has already made a sale before we realize it. She does her trick and we make our decision – the how is often hidden, so much so that the best salesmen have titles that aren’t related to sales at all. A bad sale is one that does not hide the “how”, and we realize that we are being sold to. Like when the poor chap shows up at our doorstep with a tie and a suit.
The difference is that with magic, we give the magician the credit, while with sales, we credit our own good judgement.