It's trivial to find "random fun mattress facts" by Googling for exactly that, but thanks to link and content aggregators, instead of flipping through channels on the tee-vee, we scroll for miles with our thumbs. Before commercial interests took over the web, it was full of weird and wonderful sites by hobby enthusiasts, built in their spare time that would have random weird facts and stories. For better or worse,
that Internet is behind us now, so it's rare to come across that sort of treasure trove of a site. (To be clear, there's better
and worse today, compared to the Internet of yore.)
What's the case here, is that mattress store owners, in the conversion to online sales, have purchased, not only the adword for "mattress", but paid for all manner of SEO tricks and hackery in order to drive their site to the top of the results. Far in excess of what a hobbyist could or would bother with.
It's a long shot, but the long tail of the Internet says that this has happened at least once. Someone was just poking around came across a random mattress myth or fact page, and found out that something they hate about their mattress isn't something they have to put up with. Whether that's "being tricked" into buying a mattress they didn't need, I won't say, but it still tickles an intellectually curious itch that I didn't even know I had, to find out that it’s illegal to purchase a mattress on Sundays in Washington.
A single word query like "mattress" is vague and starting from first principles, we live under capitalism, assume everyone's trying to sell you something, and a search for "mattress" proves to be no exception. Same goes for if you search for "windows". Second link is how to get it (for $199).