Having bought several hundred used records in the past year, here are my observations.
I have looked closely at my used records which have persistent noise under a microscope and found that they have a slight roughness or tearing to the otherwise smooth groove walls that was presumably caused by damage from a bad needle. These are LP's that to the naked eye appear in excellent condition. The noise you will hear is a slight static or distortion at the more intense points of the music. Unfortunately, this type of damage is very hard to observe unaided but it seems to be quite prevalent. Visible scratches may or may not be a problem as many are just along the record surface and do not impact the needle as it plays deeper in the groove.
I agree with the posters above that stereo recordings are not better than their earlier mono versions. In general, I have found that the reissues from the early 80's on, even the ones claiming to be "audiophile" versions are inferior to earlier recordings. To me they just sound like the CD with the analog noise. They lack completely the "presence" that makes well recorded vinyl superior to digital. This unfortunately, confirms that vinyl is dead except for those who, like me, want to sour the earth for real old records. If you're planning on making up your collection from vinly recorded after 1984, I suggest you just go with high quality digital.
I have looked closely at my used records which have persistent noise under a microscope and found that they have a slight roughness or tearing to the otherwise smooth groove walls that was presumably caused by damage from a bad needle. These are LP's that to the naked eye appear in excellent condition. The noise you will hear is a slight static or distortion at the more intense points of the music. Unfortunately, this type of damage is very hard to observe unaided but it seems to be quite prevalent. Visible scratches may or may not be a problem as many are just along the record surface and do not impact the needle as it plays deeper in the groove.
I agree with the posters above that stereo recordings are not better than their earlier mono versions. In general, I have found that the reissues from the early 80's on, even the ones claiming to be "audiophile" versions are inferior to earlier recordings. To me they just sound like the CD with the analog noise. They lack completely the "presence" that makes well recorded vinyl superior to digital. This unfortunately, confirms that vinyl is dead except for those who, like me, want to sour the earth for real old records. If you're planning on making up your collection from vinly recorded after 1984, I suggest you just go with high quality digital.