MFSL are just like any other pressing. Some were better, some were not.
Sometimes the masters were shot, played out.
Sometimes the match between the original recorder and the playback deck was poor. Even though the tones aligned, the music didn't.
Sometimes EQ copies were used as the master had been damaged.
Sometimes combination of tape, eq, lathe, computer and laquers detracted.
If you can get more than you paid, sell it!
Sometimes the masters were shot, played out.
Sometimes the match between the original recorder and the playback deck was poor. Even though the tones aligned, the music didn't.
Sometimes EQ copies were used as the master had been damaged.
Sometimes combination of tape, eq, lathe, computer and laquers detracted.
If you can get more than you paid, sell it!