Why do rug salespeople get a bad rap?

Here is an absolutely charming story about how an American guy walking down the street in Turkey gets talked into buying a rug. He even still likes the rug after they've brought it home. What I really liked about this story is how the writer describes why the persuasive salesperson was so very effective. He analyzes some of the techniques used so that you would be able to recognize them if they are used on you. Is the product really a scarce resource you can only get now at this one time price? I'm not suggesting sales people are all bad or insincere; it's just that you should be able to notice the techniques being employed, and decide how you want to react.