Why do people believe Mueller?

Rasmussen had a poll ( not linked to here ) in which Mueller was said to have done a fair job.  Evidently, people buy into the hype about Mueller's "integrity" and so forth.

Why do they buy in to this?  There are more problems with that investigation than you could shake a stick at, yet these people think the investigation was fair?

When I think of Mueller, I don't see integrity, nor fairness.  I'm not even sure of basic competence.

How to explain the sharp divide?  Lots of people don't trust Mueller.

The explanation could be explained in two reasons. 

1. People believe what they wish to believe.
2. The stories being told are different, most likely.  The stories favorable to Mueller are told to people who want to believe Mueller, and vice versa.

Nobody wants to admit bias, I suppose.