What do I look for in used records?

Pmotz...I believe that the first release of a stereo record was a Dukes of Dixieland LP from Audio Fidelity. I don't have that very first issue, but I do have several other Dukes records that they issued in the months following. The audio quality of those first records was better than 99 percent of the LPs that have come out since. Audio Fidelity, before the advent of stereo, had already established themselves as an "audiophile" label (as the name suggests). I don't know if today's Audio Fidelity outfit has any connection with the old one. I have been unimpressed with their recent work.

Eldartford- Thanks for the info, I've seen Audio Fidelity records over the years but never bought/listened to one. Sounds like I'm missing something good!

One more thing: the 'bad' scratches can be nearly invisible in flourescent light. They are thin but deep, like a knife cut, usually the needle causes these. They almost always have a harsh 'tick' sound.
The 'non-scratch scratch' (called 'scuffing')are broad marks from brushing the LP against an object. These marks often make no noise at all. (if you cannot feel it with your finger or fingernail, it will probably play without a ticking noise)
Cleaning is all important. The dirty looking ones often are easier to clean, wash 'em and play! The clean looking ones sometimes have an overdose of dreadful grunge buried in the grooves, that is really hard to get out. they sound terrible until they are properly cleaned. They need to soak! to get that stuff out.

Wonderful, thorough introductory remarks, so far. My only extra thought is that certain scratches are less offensive sounding than others. If you find a famous performance or recording you really want to hear you can still take a chance that the basic audio and musical quality will make a $1 or less expenditure worth trying. Sometimes overlooking one or two "skips" lets one hear enough to still appreciate the magic left in the forty to fifty year old grooves. If there are multiple scratches try to pay only 25 cents. After trying a few, if the ticks and pops annoy too much then in the future go only for the visibly clear surfaces. Clear surfaces do not guarantee good sound, but it gives you a better chance.

Wdi...You can tell if a record is stereo or mono by the appearance of the grooves. Grab two records that you know are stereo and mono, and see what I mean.