The residue people are feeling could be residue left over from something else. I don't know how likely that is... but I had a lot of residue in the back of my hair from Mane N' Tail shampoo and conditioner (never use that stuff) and when I started washing with BS I felt more and more of the residue until eventually I started feeling less and it was gone.
Sometimes when something really cleans your hair it like can bring residue out of hiding.
updated by @rose: 07/10/15 03:18:42AM