Like most monsters, Bugbears generally just paint their face and wear some kind of bandana or du-rag on their head. If you've looked at the Wiki page, it mentions paint designs like the raccoon mask and the blood mouth. Those, in addition to the sleeve, are probably the most easily distinguishable features of a bugbear.
I dug up an old picture of Vo'kor to give you an idea of what they're supposed to look like:
![Image](http://i300.photobucket.com/albums/nn2/aleytiger06/VokorinhistruegloryBugbearSW06.jpg)
Red over mouth=blood mouth.
Black over eyes=raccoon mask.
Pretty simple.