You can't know for sure sure what you have until you clean it and play it but the information on the audio asylum thread can serve as a guide. None of it is a secret but the thread is a nice concise collection of useful information. For example, anything mastered at Sterling or Masterdisc by Robert Ludwig is worth checking out. But there are many others like KP(Ken Perry), LH(Lee Hulko), GK(Gilbert Kong). Discs mastered at Kendun(Mushroom's Dreamboat Annie for example)usually a good bet. I used to think The Eagles Long Run and The Guess Who's Greatest Vol 1 were good sounding discs until I found pristine copies that were flat sounding. Turns out the good ones I have bear the TML(M or S)stamp(The Mastering Lab)Same for James Taylor's JT. No guarantees, just other indicators along with early pressings, no barcodes and good condition. Look up the thread. It details more than I can.