We’ve known for a while now that some mobile carriers have been instructing their sales staff to start pushing their customers away from Apple’s (AAPL) iPhone and toward Android or Windows Phone devices. The reason is simple: carriers pay a lot more to subsidize Apple’s popular smartphone than they do with other devices and they’d prefer to have higher gross margins at the end of each quarter. But now a Tom’s Hardware reader reports that a Sprint (S) representative has taken pushing non-iPhone products to a whole new level and is actually insulting people who insist on buying the device.

When the customer told the Sprint representative that he wanted to get an older iPhone 4 for free as part of his upgrade, the representative called the device “a piece of s—” that breaks too easily and is too small for many users.

Instead, the salesman recommended that the customer by a Samsung (005930) Galaxy S III. When the customer again refused, the salesman took things a step farther and told the man that his fingers were simply too fat to use the iPhone and that he’d need a larger screen to use a smartphone properly.

Needless to say, these up-sell-by-insult tactics weren’t exactly effective for the salesperson and the customer angrily stormed out of the store without buying a new phone.