I had been washing my mf chenille mitts after each use (Tide and migrated to mf detergent) but I noticed after several washes time they have gotten darker than the original bright lime green.

I had put them in a bucket of regular car soap (not Opt brand) and noticed the water instantly darkened as dirt/residue ONR was still in the mitt so clearly I am not getting them clean enough. I have not had any issues getting normal mf towels clean since I have been able to get some nasty stains out in a normal wash.

After noticing this, I decided to soak them in hot water with Dawn and the resulting water turned dark. I am repeating this again so I am wondering what would work faster than Dawn (they are still soaking as I type this) the next time.

Can you use an all purpose cleaner like Power Clean?

Are you machine washing them in hot water?
I have used a Cobra 530 MF towel with ONR and when I washed it with my other MF towels it appeared clean. I didn't put in a bucket of soap to see just how clean it was, though. Maybe I should.

I use microfiber towels and cloths from Towel Pro's and The Rag Shack and never have these problems... Try adding a bit of vinegar to the water as well, that should help break stuff up. I wouldn't see why you couldn't even add a little Power Clean to the hot water in a big sink or such. Letting it sit may not be enough. Hand agitate it and then rinse and then throw into the washing machine with hot water and vinegar.

I do use vinegar when washing my MF products, but I use it in a second rinse rather than in the wash or first rinse cycle.
My understanding is that the vinegar is supposed to break down the soap residue left in the towels and let them rinse cleaner.
If the vinegar does work like I think it does in breaking down the soap, it doesn't seem like it should be used in the wash cycle.

As is often the case, I may not be correct in my thinking. Any others have some input?

I'm sorry, not vinegar to the washer machine I meant to say detergent. It was late, I was tired sorry. I myself haven't even put it in my washer machine and dont plan to. Usually I clean my towels in the big laundry room sink with the vinegar, soap and hot water and I let them sit, then agitate and then let them sit for an hour or so and THEN throw them in the washing maching with detergent (no softener of course) and put the cycle on hot (which on mine is just warm).

Still, the vinegar helps to break up the remaining soap AFTER the washing cycle, during rinsing.

I wash in longest cycle (usually warm/warm) with second rinse with DP Mf cleaner. The towels seem great. It is just something about these mitts. Maybe I need to add a bit more detergent when washing them and do a pre-soak.

I am going to soak a couple drying towels that I use with ONR with to see if my towel cleaning process can be improved.