Perky salespeople annoy me to no end. I always get the impression that they think I'm some deaf old lady who's either extremely dumb or very confused. If I wanted help, I would go ask them myself. Of course, when I do ask, they act as if I'm the one inconveniencing them.
I bet whoever is training these salespeople is telling them that the customer isn't always right but that the customer is always an idiot.