I just don't get mattress stores. How can they possibly stay in business selling *only mattresses*? And it's not just one or two places -- these stores spring up like mushrooms! I'm reminded of their existence around federal holidays, when advertising appears in my mailbox: Labor Day Mattress Sale. Weird. [looking at ad] ha! There's *24* locations of just this one chain (a chain!) in the Bay Area. I really don't understand. There must be huge profit margins in this business.