From the retailers named in the comments, I gather that most of the commentators in this thread buy their vinyl at a distance, using the internet or an 800 number. When a record store is available, it does have one advantage in dodging defective records (or discs): you can unseal and examine the album in the store in front of the salesperson. The surface should be pristine. If there's any question about a defect, a player should be available to test it.
I occasionally bought used CDs at Amoeba in LA. Because the inventory was used, it was mostly unsealed, and there was no problem with examining the disc before you purchased. Sometimes Amoeba would reseal albums that it considered to be in very good physical condition. I wasn't persuaded, so whenever I considered a resealed album, I asked the salesperson to open the album so I could examine it. I distinctly remember rejecting potential purchases on two occasions.
I occasionally bought used CDs at Amoeba in LA. Because the inventory was used, it was mostly unsealed, and there was no problem with examining the disc before you purchased. Sometimes Amoeba would reseal albums that it considered to be in very good physical condition. I wasn't persuaded, so whenever I considered a resealed album, I asked the salesperson to open the album so I could examine it. I distinctly remember rejecting potential purchases on two occasions.