Too bad I didn't take a before photo. I brought the mat inside to vacuum it with the house vac, with a beater bar. It's then I noticed that the center portion was nearly black on a medium sand-colored mat. It had been awhile since I'd paid much attention to them beyond the periodic vacuuming using the shop vac. So I tried a quick clean using a can of Tuff-Stuff cleaner, a liter of 145°water and the shop vac. I sprayed the center section thoroughly, rubbed in the foam well with a soft carpet brush in two direction, flooded the area with the hot water, then sucked it up with the shop vac. I repeated this on the worst sections till I used up all the water. The water in the shop vac was jet black. I then rubbed my hand across the nap and noticed dirt particles and dirty water on my hand. Hmm..needed more rinse. I spied a large poly storage container big enough to hold the entire mat, dropped it in and began to hose it off. The contained water quickly turned murky then black. OK..worse than I thought. Next step was the vertical washer, set on the gentle cycle with warm water. I left the lid open so the cycle would stop before draining. Still quite dirty, though better. So I let them soak for 45 minutes, then ran another aggitation cycle and let then soak again, then let the cycle finish. Since the gentle cycle doesn't spin as fast as cotton, I flipped the mats around so the pile was facing outside and ran another 'rinse & spin' on the faster setting to sling as much water out as possible. Then into the dryer for 15min on low heat. I hung them up inside because the outdoor humidity was > 90% and let them dry overnight. Cleaner than I'd seen them in a very long time! I've power washed them, scrubbed them with Tuff-Stuff, hung them up, then rinsed with a jet of water, etc. but none worked as well as this. BTW, the hot water extraction I did in the dirtiest part of the mat did make a difference as this area was lighter than the rest after they'd dried. Next time I'll juggle the order a bit, but I'm pleased overall with the results. Another BTW, I have light grey color carpet in my house. All modern carpets are designed to be cleaned with hot water (steam) extraction. That's what the pro carpet cleaners do. You can replicate this on a small scale with hot water and a shop vac on most stains. Works like a charm. If you ever spill red wine on a light carpet, use cold water instead and rinse several times. Then use the Tuff Stuff, work the foam in well with your fingers and it'll turn the red to purple then blue, soak the stain with cold water, then suck it up. It'll disappear! I was amazed. Let it dry before walking on it. I can't even tell where the spill was!