buy one get three free.

The phrase is in practically every late-night tv commercial selling some kind of new mop, towel, paint, or cleaner. 

And most people, if they see the ad, ignore it. They see it for what it is: a blatant attempt to sell something, that isn't good enough to sell without some kind of ridiculous enticement to get your attention and money. 

But, lots of people purchase those items - and they aren't all dumb people. 

The ads are everywhere. 

Buy one fear, get three more thrown in! For free! 
Buy one enemy, get two more! But only if you buy now! 
Buy one hate, get a dozen more. Free! 
Buy one lie, you'll get to believe five more! No extra charge!
Buy one pessimistic outlook and gain an infinite number more! 

We could go on and on and they're all about as worthy of your time and money as the miracle tile cleaner that will make your bathroom look new in 5 minutes, without a drop of sweat. 

Yes, people will purchase them. They always do. But don't be one of them.