I agree with Bdgregory that the look (and the smell) of the cover is irrelevant to the quality of the sound to be heard from the record. Even if the record is dirty (dust, finger prints, etc.) it is not tragic (it should be washed thoroughly). Essential for the quality of the sound reproduction from vinyl record is, that the disc is without (deeper/auditory) scratches, that it is flat, not "exentric" and that the grooves are not deformed/damaged by the previous playing (with a deformed/worn needle, improper setting or playing unclean record). The latter is hardly to detect without playing the record on the turntable.
Tips for buying used Vinyl needed
I see there is a learning curve to buying used vinyl, can you please offer your wisdom and experience? In my recent attempts at buying used vinyl I have learned not to buy from someone who has stored their collection in the garage, dusty, moldy, and urine smells are gnarly. I am starting to look closer now that I have brought some home from my local shop and noticed imperfections in the vinyl itself, resulting in pops. Finding thirty and forty year old records in good condition is not as easy as I thought it would be.