[curun1r]

That's the point behind mattress covers/pads. For $50/$100, you get something to put on top of the mattress to absorb the dirt. After a few years, you can replace them for a fraction of the cost of a new mattress. They can also be removed and washed.

[cvburgess]

Covers are great (I have and use one) because they keep sweat and dirt out (which kill mattresses the fastest) but they do not prevent the mattress itself from deteriorating due to constant weight.