In sales, it's all about how you word things. "And this price includes the extended warranty" is better than saying "this is your price, and if you'd like to add the extended warranty it will be $XX."

This isn't really a dirty secret, but rather a tenant of sales in general. It's called top-down selling.

You start the customer off with the very best product with all the options and only when they balk at the price do you start working with them. Bad salespeople are afraid of the awkwardness of customer interactions and specifically the "sticker shock" when they quote the price, so they start with a low price and try to fight the uphill battle of presenting all the different options one by one, which of course the customer will turn down if given the choice, even if they're good options.

It's a weird psychological thing. Let's say the product costs $500 and the customer is totally willing to pay it. They're going to be far less likely to be willing to pay it if you start at $200 and then dink and dunk them with add ons that gets the price up to $500. It's the same product with the same options but you've now talked yourself out of a sale because of how you presented it to them.

The way I describe it to my team is the iPhone example. If you walked into the apple store and said you wanted a new phone and the salesperson was afraid of your reaction to the price of the new iPhone and therefore only presented you with the iPhone 2 you'd wonder if they were incompetent.

In the end I always explain to the customer exactly what they're getting for the money, but I just word it in a way that some might consider dishonest or sneaky.

TL;DR -- Being good at sales means toeing the fine line between honesty and total shit-headed subterfuge. The difference in making a sale and having a customer walk is how you present it to them.