One of my favorite word twists, which I think I only ever used on my blog, is "common groove"
Basically I have this perspective that the best black music, whether it's funk or disco, tends to be the most commercially successful stuff. The cream rises to the top.
Because of all these obscurantist reissue labels, you have a generation of hipsters who have listened to all this objectively second or third division disco, funk, etc - but never actually listened to Rose Royce or Stevie Wonder or whoever - the stuff that got into the charts and that masses of people bought and listened to.
All that stuff is common groove because there are loads of vinyl copies lingering in the world, going cheap - and full of wonderful music. You could probably pick up 7 albums worth of it for the price of one of these stupid reissues.
It relates to Northern Soul actually - that was the original 'rare groove' although they didn't use that term, they talked about "rare soul".
They had a whole inside-out perspective where they wouldn't play Motown because it was 'commercial' - meaning simply that it was so indisputably good that normal people liked it and bought it!