Whats the best record cleaning fluid?

Try and see if you can get hold of the purest lab grade alcohol you can find. Ditto the purest grade water. Mix 25% of the alcohol with 75% of the water to use for cleaning your lps. Keep both the pure,unused alcohol and your 25/75 mix in glass bottles or jars, NOT plastic. When I used this mix, the degree of improvement in the purity of the sound quality of my lps was quite significant. Over the years, I had tried several of those market solutions, but, to my ears, they rarely made things better. (Yes, I know, opinions and impressions do vary.) There are a HUGE number of gimmicky, questionable and absurdly overpriced "solutions" out there in today's so called audiophile marketplace. Caveat emptor.

...and to that 25/75 mix add Purple Death (a few drops).

Psychicanimal : Watch it ! You may get a visit from the Charmed Ones. (Actually, that wouldn't be too bad.)

What the h is Purple Death already? Maybe I don't really want to know, but I have never heard of it and you are the only one I've ever seen mention it.

Dumb question, but where do you think the dirt from the record goes?
Into the brush which then requires cleaning itself?
Or is the dirt removed by the RCM vacuum action?

Or another way, is the RCM more of a cleaner or a dryer?

I'm open to percentages here!

Thanks