Mark Lacter of LA Biz Observed has a readable LA Magazine profile of the Sit 'n Sleep chain and its owner Larry Miller. He tells Lacter he decided to switch from quirky ads featuring, for instance, Miller's visage on Mt. Rushmore, to a health gimmick.
Miller said he read somewhere (um, where exactly?) that a mattress will double in weight after eight years due to the buildup of dead skin cells, sweat and the fecal matter of dust mites. (Thankfully, he left out other examples of things that might weigh down a mattress.)
Lacter checked around, and the claim seems to be a bit of flimflam scare-mongering. Dust mites aren't dangerous unless you're allergic to them or have asthma, and the doubling in weight thing is just a little hard to believe. (Needed: A mattress scale.)
But hey, give the guy a break, he's selling mattresses, not pharmaceuticals.
Indeed, Lacter also has a nice discussion of the overall weirdness of the industry, noting how difficult it is to comparison shop, with the added gamesmanship required because of the inevitable haggling. (Why are some businesses all about haggling, but others you just pay the price? You don't haggle at Barnes and Noble. Though maybe you do at the local used bookstore.)
In any case, the guy's been very successful, so there's that.