Record cleaning is essentially a fetish within the vinyl world. One has to balance their pursuit of a quiet record with the stupidity/nostalgic nature of the medium. Face it, no one would "invent" vinyl records today as an audio storage/playback mechanism. Even a new record is never as quiet as digital, and to expect a 50 year old slab of neglected toxic waste, that was acquired for $3, out of a dusty bin, to play noise free, is delusional.
Record cleaning is no different than sighted audio evaluation. People that spend hours scrubbing and drying, or those that spent $$$ on fancy machines, will tell you these devices perform magic. Bull. Only a new record can be somewhat guaranteed to be undamaged and unworn. Any noise left behind after any of these cleaning methods is record damage, as all of these cleaning methods are adequate to clean a record. The OPs observation that his results improved, when he washed correctly, indicate such.
In a silly medium where sound is reproduced by dragging a suspended rock through a canyon of vinyl, reproduction of the original signal can only be achieved if the canyon is free of external debris. External debris encountered by the suspended rock will either be pushed out of the way and dragged behind the rock (dust build up on the stylus), or will be rolled over by the rock, with unmusical noise as the result.
Which means you usually gotta clean used vinyl records.
The least OCD method is to use a method that cleans one record as you play another, without actually having to stand over that record to clean. Otherwise you have a "cleaning vinyl and listening session" rather than just a "listening session." The machines that spin both sides of a record, continuously and quietly through solution (while you sit and listen to another record), and then dry quickly with a vacuum blast (during record changes), are the least OCD way to clean records.
I don't know if any of the ultrasonic cleaners allow for a quick vacuum dry, but they do clean both sides simultaneously. The
Nitty Gritty Mini Pro 1 wets, scrubs and vacuums both sides, with the least hassle of any method. I do not recommend this machine because it is better, but because it makes the record cleaning process easier. It is definitely not cheap, and no record cleaning machine is, because the economy of scale for production is non-existent. This machine, and its associated precious fluids, is inadequate!? Refer to paragraphs 1 and 2.
Vinyl (and reel to reel tape?) is already such a time suck, that the normal rituals/hassles/TIME, of just playing a record, require a "listening session." Why add to that with OCD cleaning rituals?
BTW, if there is another machine that performs quiet, unsupervised, cleaning with simple vacuum dry, please inform. Does the Kirmuss machine, for instance, vacuum dry within the machine, after some sort of fluid drainage?
For reference, I own ~1500 LPs, and wish I had bought the 2 sided Nitty Gritty, instead of the 1 side at a time, Nitty Gritty.
Listen to, don't obsess over, your LP collection.