LP's... Do they sound better now than 30 yrs ago?

@inna - happy to engage in a little experimentation with you; just send me a PM. I am a little unclear about the protocol you are proposing because no two records are the same, and if we are talking about older records that have seen some mishandling, bad past cleanings, etc. they are likely to be markedly different specimens. Shoot me a PM and we'll work something out. 

I will. Those two copies I have sound exactly the same on my table except one has more scratches, that's the one I would send to you.
Acoustic guitar music, Japanese vinyl from mid-eighties. 

Inna, that’s fine. Just to be clear, I’m not talking about fixing scratches, it’s more the distortion that you hear when it sounds like the record has been played on a bad record player and the groove noise is high- to the point of distortion. Also, what I call tracing distortion, which is similar- you hear a sort of etched sound from what may have been a misaligned tonearm/cartridge (crystal needle anyone?) from a kludgey old fashioned record player. Sometimes, not always, those kinds of distortion are just a result of crap in the grooves that has been cemented in and it isn’t easy to get it out. Thus, the maniacal cleaning regime on seriously scarce copies. If it is a cheap record, I often just replace it if a couple of cleanings don’t do the trick.

This is going to be fun. 

Here's another 2 cents worth: I have occasionally picked up a rare record in amazing condition at a thrift shop for a buck, whats cool is some of the 60's vinyl is really resilient, and old beat up mono lp's CAN sound amazing with a dedicated mono cartridge (think Audio-Technica AT-3or 33 and others) which seems to eliminate most of the surface noise that a stereo cart will pick-up, HOWEVER if you only have one turntable/tonearm you will want to change the headshell out for ease (maybe an old Technics1200?) for this, another reasonable bullet proof turntable, (as long as it hasn't been DJed to death)