One of the things that I continually vacillate on when I try to use a rating system is which rating to pick. It’s an over-analytical thing.
Is there a way to change the popup description for when I hover the mouse over the stars? Currently, it always says “rating,” but it would be nice if I could have it give me a reminder of what each star is representing. I know it’s a long shot, but I’d thought I’d ask anyway. 
Doesn’t any rating system mean whatever you want it to mean? If you think “5” is “best ever” and “1” is “worst imaginable”, then that’s what the rating means. Conversely if you think “5” is “avoid at all costs” and “1” is “must read every day”, then that scheme is also supported.
@korm is correct on this. Consider these two simple examples. Same scale - 1 to 10, but different meanings…
That girl is a 10 !!! 
Think of the poor dear who’s just a 1.
We’re number one! We’re NUMBER ONE!! 
No one celebrates they’re number 10.
Sure, if you use the rating system that way. But I was thinking of using it to rate the quality of the information, I actually wouldn’t keep anything that’s rated a “1” as it wouldn’t be worth keeping. I might not even keep a “2” for the same reason. Thus, 1-5 stars would need to take on a different meaning from the classic rating of 1-5.
But, if I gave each start a meaning - and that description popped up as a reminder when I hovered over it - the start rating could be more useful. Something like:
5 - Great info; excellent for public reference and dissemination.
…
1 - Dubious or needs vetting; internal use only.
2, 3, and 4 would be a sliding scale between them.
Then, when searching, I could limit the results to only the quality I need at the time.
We can configure names for Labels in DEVONthink preferences, so I suppose @robh you could request similar for ratings, if it’s hard to recall what stars indicate.
Or you could set up a custom metadata set using the desired descriptions.
I completely forgot about custom metadata, which of course will fit the need. The only issue I have is that the custom meta is on another panel. It’d be nice if we could put some of the custom entries at the bottom of the Generic panel for convenient use.