I use many, (everything with 2, 3 buckets, foam cannon, and many brushes)
Meg's MF Mitt for general prep. washes, good and durable mitt. I machine wash this mitt after using it. Yes, it comes out pretty clean after a wash, but I like to keep it cleanest as possible.
I don't mix it with dirty MF indeed, but adding just one more item to a 'paint safe' MF wash load is that easy.
Even though I soak dirty MF enough before machine washing for a cleaner load.
I'm an **S regarding my MF care, although I have many, I like that those many are always in flawless condition, so I can chose any, the clean one closest to me.
Micro-Chenille Mitts - have many, color coded, so I can use some for bellow parts, etc.
They work good, but the AG versions are better than general ~$1.99 dollar store. They are 'fluffier' and softer, a bit larger as well. However, they seem to be made in china too, so in china you can find both versions, the good and the 'bad'.
That only means general sellers offer the bad version, while AG always ensure to put a selection of better quality products, even made in china products. So ordering at AG will guarantee that you'll be getting the better version.
Gold Plush Chenille Mitt: This one (from the above, but color coded) NEVER saw dirt in it's existence. It's dedicated for polished paint, I just use this one for before LSP washes (I do in 99% cases in context I work). I call it 'dedicated to polishing oils'. Even my wife is somewhat 'jealous' about this Gold Mitt, no one can touch it but me, it lives almost 'in a bubble'.
My mother asked me once it arrived if we can take a shower with Gold Plush Mitt, it's glamourous. (I couldn't answer! aahahha).
I wash it after each use together with paint safe polish removal towels and the drying towel used for last dry before LSP.
CarPro Merino Wool Mitt - I ordered this mainly because of RAVE reviews it receives, and man I need to say I'm impressed. It's probably one of the most luxurious item you can glide over a car's surface.
It's that good because it offers immense softness while providing great tactile feedback on slickness. It's easy to notice when it's time to rinse the mitt / add soap by slight increase in drag resistance. IMO, this one provides the SAFEST wash possible (comparing to above I've cited), which I reserve for maintenance washes. AH, it cleans very well too.
Downside: It may 'lose' some wool fibers on crevices / trim raised parts, it's not crazy lint, but I found myself removing some fibers after using it from 2-3 different places before I become aware of this issue. Now I just take more care when using it around those areas.
However, I'm used to find 'old rag lint' stucked into trim raised parts, so if a customer find my wool mitt fiber someday I would say: "Hey dude, that's Merino Wool, it's cool!"
The Merino Wool mitt is not recommended for machine wash, so this one I only Rinse it very well, then shake it (imagine how a Merino would do to dry itself after being washed hahahaha), but it'll drop water all over you...
I don't mind getting bit wet that time because shaking the mitt like a merino would is a great way to loose the fibers and makes it return to like new state, will dry much faster as well. Then hang it dry.
The day after I use a pet brush to brush it... No kidding! It's like another pet...
Hope that helps,
Kind Regards.