This is a hackneyed phrase from any sales industry. The idea is that if you pitch any product to enough prospects, you'll sell enough to make a living. It's a way to get the sales force motivated to work more hours than any human could. Of course, if you're young and energetic and you've never made any real money in your life and this is your first big toe in the waters of living on a commission, it does have a real appeal. You'd be surprised what good entrepreneurs can make with a whole lot of hard-ass work and a couple of viable products to sell, once they decide to quit working for an hourly wage.
Salespeople will obviously tell you everything good about a product and leave off the bad stuff. It's their families they are trying to feed, you know? Many of them are good, honest folks (not the car salesmen, forget them) with specialized educations who are looking out for you as much as they are themselves. They just realize that explaining every detail about a product (especially if it's intangible) is beyond your ken. And it would also cost them the sale if they were to bore you to death. Many salespeople fail in this sort of attempt. So it's a tiptoe through the bullshit sort of routine, usually.
After you've established yourself in whatever sales field you enjoy, you'll have enough clients who trust you that the references from them alone will make you a good living. As long as you don't lie to them for your own gain. Then you can quit throwing a bunch of stuff against the wall to see if it sticks. In fact, you may find that quick sales which don't last long actually begin to cost you money.