Items which are M/M are new Items and never played. I dont use SS because a lot of records/CDs from small publishers arrive without Sealing.As I only buy from private sellers only complete collections (I never buy from DJs, markets or second-hand stores) and sort in the forehand the minimum quality of the records is very good for nearly every record.
If it is not, it is described in the GradingDescription.
Most of the LP-records, are partly listened to and quality is insured, that it is as described in the Grading Description. Records for less than 10 Euro are at least visually inspected.
We dont listen to CDs, but do visually inspect them.
If the above policy leaves any doubts, please refer to GEMM's generally accepted Grading Standard