As is well known, most mattresses sold in the US are made in a small number of factories. In order to make comparison shopping hard, the mattress provide “unique” product lines to each major retailer. By making minor adjustments to the fabric or something and changing the (almost inevitably ridiculous) model names they sell under, Sealy and the like make price comparison shopping impossible. And they allow each possessor of a 'unique' line to make price-matching guarantees that they know are meaningless since no one else carries goods with the same name.
That's why I'm glad there is a Mattress Comparison Index which (says it) tells you which silly name is comparable to which other silly name.
Even armed with this information there is still a lot of product out there and field testing these things is both ridiculous and not particularly informative. It's easy to dismiss many mattresses as too soft or too hard, but that leaves a large range of choices, about none of which I feel confident about how they will feel in a year.
I wanted to illustrate this with a picture of Li'l Abner in his role a professional mattress tester, but while I could find some of him, there were none of him at work, which somehow seems fitting.
Incidentally, I was surprised to learn that professional mattress testers really exist!