It is actually fairly plausible that Stoppelmann has no idea at all that his sales representatives are using such shady tactics.

That is not, however, good news for Stoppelmann. Not in any sense. It would indicate that, at the client-business level of interaction, there is no functional oversight at all. That Yelp's management's either willing to turn a blind eye, or are so negligent as to allow this to occur even in the face of growing criticisms.

Incompetence or malevolence; either way, they're in trouble.