What do I look for in used records?

I like the local used record stores here around Lancaster, Pa., and the Pa.Record Expo that meets here monthly. I also like the guys that grade the records and I go for near mint, mint or VG+. Having said that, I look for a record that has no visible scratches. Dirt is ok, as I can clean it off. I went to the local Goodwill, and got some as a result of reading posts as well. Got a record that looked as though it met my criteria, cleaned it and lo and behold it sounded terrible. Pitched it. Also, if the person who owned the record previously put in a new sleeve, I tend to feel real good about it. I recently bought about 7 albums for a quarter a piece, with the covers pretty beat up. But the records were in new sleeves or at least looked good, and they sounded great(Record Expo). So, I haven't answered your question specifically, but I don't know the answer to your question specifically. Find some places you trust and enjoy yourself. Check other posts for cleaning procedures.

To add a little bit more to the above posts, the first mass produced stereo recordings were available in the late 1950's. I believe they were predominately classical releases (someone correct me if I'm wrong). The collectors go primarily for the RCA, Mercury, and London records (from this era). As for identifying the stereo versions the RCA's are of the LSC-xxxx series (Living Stereo) and the Mercury's are of the SR90xxx series (Living Presence). I'm not so sure about the London's, I know the early issues are identified by their light blue back (of the jacket), but I don't know if they are all stereo. As for the mono releases, the RCA are identified by LM xxxx and the Mercury are identified by MG09xxx. With respect to the album Wdi found, it is a mono and probably predates the first stereo releases (1957?).