I know this might seem like a broad question but hopefully I can clarify. I recently bought a record player and am starting to build a collection of records because I like the experience of hearing the original raw versions. My concern is if I buy a brand new record of an album that came out 30+ years ago, am I getting the original quality or just a pressing of a remastered version, and more specifically how can I tell? I hate to spend $40 on something that is the same quality as a CD or digital.
As I said in the comments, it really depends on what you are looking for, and probably on how you define yourself : Are you a collector or a listener.
Collectors will look for the original released vinyl record, and focus and rare stuff. For example, Rolling Stones album Some Girls was censored shortly after original release. So, there is only a few existing original discs today.
Here you can see a list of Controversial Albums and some were banned and reissued.
Of course, there is a large amount of reissues, represses today which have probably a lower maket value.
The initial release of the Beatles album Yesterday and Today was sold 25,600$ at an auction. But you can buy represses for 2$.
So, Collectors will look after rarity, history, fun facts more than audio quality. They probably won't listen this copy to avoid using it more, they just want to have it.
Listeners will focus on audio quality. Original copies, i.e. older ones have been played much more that new ones so they can be slightly damaged over time (don't forget playing a record consists on a diamond running on the disc groove, hence each time damaging it a tiny bit). Also, old releases have used old mixing techniques that (for some people) can be considered as lesser quality.
Older versions of the Beatles album With the Beatles were Mono, newer ones Stereo with a weird panning (100% left or right).
It that case, it depends on what the listener prefers.
For brand new records sold today, there is a chance that the cover (or inside sleeves) describes the material used for this reissue. You can also check on Discogs for additional information.