Listen to one, clean it and compare. If you don’t hear an improvement, why bother?
Cleaning your records may or may not reduce surface noise, but I’m confident it won’t add any if done properly. I’m also confident it will protect and extend the life of your stylus. I’d suggest cleaning all your records (and any futures) with the Spin Clean, replacing any paper sleeves and then using a record brush before play.
My own personal record cleaning experience started with a Discwasher w/D4 fluid (pad system). It cleaned the dust off but didn’t clean the surface very well if at all. It didn’t add or remove static. It didn’t improve the record’s sound. I used it before every play. I went through a couple over about 20 years. At the time, it was one of just a few ways available to treat a record.
As I moved up the analog food chain, I went to a VPI HW16.5 cleaner. The records came out dust free and spotless. It didn’t remove static but sometimes it added it. Occasionally it improved the record’s sound, but not drastically. I used it with the VPI cleaning solution and had it for about 20 years. I was happy with it and recommend it to friends. I used it before every play.
For the past several years I’ve had an AudioDesk Systeme ultrasonic cleaner, used with distilled water and the company’s surfactant. It removes dust, static, fingerprints, stuff I can’t see but shows up on the filter, and the records look pristine. It doesn’t work miracles, old or used records will probably still have some surface noise after a run through (or two), but they can be anywhere from slightly to greatly improved. I’ve compared new records before and after, and they always sound better after a cleaning. I seldom clean a record a second time, but I use a brush before it’s played. The unit is as expensive as a component, which is what I consider it and it would be hard to be without it.
Good luck figuring it all out and have fun along the way.