While you cannot tell for sure with a visual inspection, there are a few clues that help to weed out some candidates. First, look for a lot of use of the record, such as a lot of marks on the label near the spindle hole (caused by someone sliding the record around to find the hole. Another sometimes helpful visual clue is that the playing surface on a well-worn record will sometimes appear grey and not as shiny as a newer record.
Of course avoiding scratches is the obvious way to avoid bad records. However, if it is a title I really want, I will accept records with a lot of scratches as long as the scratches are not deep. I have plenty of used records that sound like they are new even though they have a lot of light scratches; the line-contact profile of my stylus tends to play deeper down in the groove and often avoids surface problems.
Of course avoiding scratches is the obvious way to avoid bad records. However, if it is a title I really want, I will accept records with a lot of scratches as long as the scratches are not deep. I have plenty of used records that sound like they are new even though they have a lot of light scratches; the line-contact profile of my stylus tends to play deeper down in the groove and often avoids surface problems.