If all a C/D client wants is lower fees, I wouldn't classify them as D clients certainly. To become a D client for us, someone has to be difficult or contentious as well. During tax season we create a bucket list of D/E clients that we intend to have "kick the bucket" after tax season. Inevitably when we review the list after tax season, we soften our opinions and only a few make the D/E list. The issue to me is defining what clients really are C/D/E clients. Are fee considerations the main criterion?