In fact, I would more likely join them than the Dark Brotherhood, because my character never really cared that much about the whole Night Mother and Sithis thing.
Mine didn't either ... which made it even better.
![Smile :)](http://gamesas.com/images/smilies/icon_e_smile.gif)
While I was pretending to be one of them, I always secretly made fun of them and their stupid occult blabla.
![Very Happy :D](http://gamesas.com/images/smilies/icon_e_biggrin.gif)
I dunno about the thieves guild being totally evil. I actually liked how Bethesda balanced their mentalities in Morrowind and Bethesda. They weren't good or evil. They just did jobs. Some people in the guild were more rough and shady, while others were more noble and respectable thieves. In a thieves guild, such a balance of personalities and varied goals amongst members fits the concept best, IMO.
+1
And the same goes somehow for the DarkBrotherhood as well. They had different characters. Some being the occult freaks, some being just a stupid giant ork who likes to kill, some being more professional, some being kind of "born into it".
And thinking back to the mages guild, you even had some evil/apostate people there.
I think there's nothing bad about a guild having a good or bad image. But of course, not everyone in it should really follow that image.
I have never played the warriors guild (only first quests), so I don't know, how it was there. A few members could/should be corrupt, but most people in there should rather be "good" people or just people, who do it mainly for the money.