I don’t think any hard rules can be applied to this.
Steve Wilson’s 2011 remix of Jethro Tull - Aqualung is a vast improvement on the original mix. That album is a favourite of mine, but never sounded right to me. So I was very thankful for Mr Wilson’s work on it as it is a pure delight.
Another one is 2008 Shelby Lynne - Just A Little Lovin’. The original sounded pretty good. But then it was redone in 2014 by Analogue Productions and it COMPLETELY blows the original away. Just jaw dropping good. Makes the original sound dead and flat.
LOL! “First soiled diaper” got a good chuckle on that one.
Agree many remasters seem to be just a money grab. I especially abhor remastering that compresses the dynamic range, just criminal.
But then there are others that put in the effort to improve on the original to make things right and those are worth getting. And when I say remaster, not just the re EQ, but also the expert disc cutting to take full advantage of tech we have now, so for example more of the original bass can be cut into the groove. We’re as before it was limited by choice or whatever to accommodate the masses or radio.