Bob's makes a big deal over his "20 year non-prorated mattress warranty." If you look at the fine print you'll see that there can be no "staining." What they mean by "no staining" is "absolutely like new." As the tech who visited my house told me, even if the stains are removed, if the cover is even slightly discolored that voids the warranty.
So good luck on getting a replacement.
Now, we bought the most expensive Mattress Bob's sold in 2003. $1,000.00. After 6 years the whole middle started to sag. Obviously, whoever built it for Bob's used cheap metal in the springs. I looked at the cutaway in the store of a Bob's mattress vs. a Sealy. His looked so much better. What I now think is what people were shown in the store and what arrived in my house were two different things.
Bob's is a "take the money and run" kind of place. It just took me a few years to figure that out. The "everyman's guy" who sits on the couch and tells you what a good deal his stuff is fiction. Beware.