They're thugs/mercenaries that intimidate and even kill for gold.
They are always talked as being honorable but what honor are they even talking about?
I don't see honor in having a fist fight with an inn keeper over a situation that they don't know or care about.
What if the person that they are thugging around with is an innocent person and someone just wants to cause trouble for them?
How do they even get authorization from the Jarls to do things like this?
The Companions seem like an openly accepted borderline Dark Brotherhood.