As stated, it's a crapshoot. Mishandling: spindle hole damage, ring wear, lack of original inner sleeve, etc. are warning signs. But, I think the biggest risk is vendors who know the tricks and dress-up old records by polishing the vinyl, cleaning the jackets, replacing missing inner sleeves. I see this at audio shows where hucksters are asking very high prices for "rare" used and nos records, many of which are available new or re-issue from legitimate sources. Some show vendors offer headphone listening, but crank the treble down to hide audible hiss. Also, warp is a real risk on sealed nos stuff.
My personal rules are buy lots of cheap (> $1) stuff at thrift stores and garage sales and expect to re-donate 90%. For moderate stuff ($5-$10), deal with reliable local vendors who will accept returns. For audio show vendors, leave your credit cards at home.
My personal rules are buy lots of cheap (> $1) stuff at thrift stores and garage sales and expect to re-donate 90%. For moderate stuff ($5-$10), deal with reliable local vendors who will accept returns. For audio show vendors, leave your credit cards at home.