The other motivation on garbage B-sides is songwriting royalties on the record sales. Spector took full writing credit on this one, and the songwriting royalties for the B-side were the same as the songwrting royalties for the A-side. He messed up on the garbage B-side bit on "Hung on You", as he stuck Bobby Hatfield singing "Unchained Melody" there (No Bill Medley involvement at all, songwriting royalties went outside), and it got flipped of course. "Cara Mia" by Jay & The Americans was meant as a B-side. "Na Na Hey Hey Kiss Him Goodbye" by Steam was meant as a B-side. There were lots of others. Sometimes records got flipped by some DJ's, not by others, and both sides charted but ended up in the nether regions of the charts. BTW, England didn't get the message on "River Deep, Mountain High", and it was a huge hit there (as was 'Pet Sounds'). And Englad actually got "good" Herman and the Hermits 45's, not "Mrs. Brown" or "Henry the Eighth". Etc. But it works both ways.