What should I look for when purchasing a quality album?

I'm not sure anyone has mentioned Goldmine rating scale for used records. This is important to know IMO.Learn it and you will know how much snap crackle & pop will be in those grooves. You can do this just by looking at the album. A good dealer/seller will grade the record properly. Unfortunately, the vinyl resurgence has brought a lot of people into the sales end who know little or noting about Goldmine. Their description says something like, "looks great" or "no skips". Some will offer a play graded album with their cheap blunt stylus TT which they will say sounds good. And it may ...to them. But a properly maintained and setup TT will show the flaws.The truth is you'd better stay away from those people.

I don't buy many today because I bought most of mine in the early 2000's. But I wouldn't buy/play anything less than a VG+.

Goldmine

@lewm  Don't you know that all records are very valuable now?

Seriously I  agree on value. I'm not sure I have ever used their value as a guide. But their grading scale is very good. Of all the used albums I bought back in the early 2000's, I made one bad purchase. The records had been well cared for and looked VG+-NM. I then learned about groove damage and how it sometimes goes unseen. I think I even payed $3-$4 apiece for them. That was expensive back then. I'm so glad I got back into vinyl early on before the resurgence.