fast talker

A person who verbally manipulates others into doing or believing something, especially something that is not in their best interest. I could tell that he was a fast talker just by the way he tried to close the deal so quickly. Used car salesmen have a reputation for being fast talkers. They'll say anything to sell a car. Mom, do not give Rich money again. He's just a fast talker, and all of his so-called "businesses" fail.

a fast ˈtalker

a person who can talk very quickly and easily, but who cannot always be trusted: The salesman was a real fast talker, and somehow managed to convince me to buy the most expensive model!