I have a GENEVA brand bulk audio/video tape eraser. I bought it for $99 about
ten years ago and don't know if it is still available. It does make a difference.
The sound is cleaner/clearer and dynamics are improved.
LP's do get magnetized. I've read that it is not the ink on the label, it is the
metal in the vinyl formula that is used to make it black. Over time it picks up a
charge. I don't really know the how or why, but I do notice an improvement. I
demag an LP once after I clean it. It is part of my cleaning regimen. I also use
the Cardas sweep LP once a week to degauss the system.
The more revealing a system is, the more noticeable this stuff is, IMO.