Second hand vinyl surface damage.

I’m probably more tolerant than most audiophiles. But if there are any grooves that either skip or repeat, if there are grooves that display significant distortion (from being chewed up by a previous owner), or if the noise floor becomes overpowering for even rock music, then it gets put into the "do not play" pile. Deep scratches that yield a loud "pop" an 2 second intervals can be awful, and I judge them on a case-by-case basis. Occasionally there will be a record with a single extraordinarily loud "POP" instance - and then I try to find a baked-on piece of grit that caused it so it can be cleaned off. Of course, when a record is a bit noisy I will play it, but if I really like it I’ll try to acquire a better copy, eventually.

I visually inspect vinyl at local stores. And on DiscOgs I aim for VG+ or NM, only going down to VG if absolutely necessary. With this, it’s relatively rare to encounter a record that fails my playback criteria. It’s more likely that the recording/master/pressing just sounds "blah", and I will not want to listen to it again for that reason. But that's the value of vintage vinyl - they tend to sound better than most reissues. So I find it extremely worthwhile to buy used. 

I do have one record I love with a failed end-groove (Dust - Hard Attack side A), but no other playback issues. That’s no fun, when you get to the end of a side and your expensive MC stylus is sent careening into the paper label (a water damaged label to boot)!

played 3 out of 4, didn't even clean them, essentially noiseless. will play 4th tomorrow

If this has already been noted sorry for the repeat.  If you are buying an LP that had one or two blockbuster hits check those tracks to see if they look more worn than the rest.  If you see this you are probably looking at a record that was purchased new by someone who knew little and cared less about record care and preservation.  They probably also used a table/arm/cart combo that caused excessive wear and groove noise every play.  This can the worst defect of some used records and one of the hardest to detect visually.  So if you find a mostly pristine looking first edition Led Zep but Stairway to Heaven looks noticeably duller or different in any way from the remainder drop it fast.  Sorry that this doesn't help online buyers.

Unfortunately and IME the only way to truly determine the condition of a record is to play it! I recently acquired what looked like a Mint copy of a little known Direct to Disc. This LP was graded Mint minus, and looking at the sleeve and the record, the grading was correct. The record was cleaned with a Ultra Sonic cleaner and played. Result..tremendous hash and noise, particularly between tracks. Very sad, as the record has great potential and is hard to source. Someone in the past had played the record with a worn stylus and not realized the damage caused.

@daveyf if you haven't already, try a second thorough cleaning.  Sometimes by cleaning and playing a used LP, especially something like a D2D, old ground in dirt gets loosened and more noticeable in the sound.  No guarantee but the second cleaning can really help.