Just to make sure nobody else does the same thing as me today...
My 124 flootmats were filthy so I went ape with the Shout carpet cleaner and then took them to the car wash to use the high pressure water on them.
I got them home, then put them on the deck in the sun to dry out. Well the wind kept blowing them off, so I thought I'd put them in the clothes dryer for a while.
Uhm... don't do this.
It tends to break down the black material on the underside and make one hell of a mess. Luckily I checked them before the cycle was up. I had to take the shop vac and suck out the dryer from all the black particles everywhere. What a mess.