[img]smilies/evil.gif[/img]... 
  I am no expert on LOTR's I have never read the Sil, book of lost tales or Tolkiens letters.  I know very little about Mos, but I do have somewhat of a theory on why he spoke the name of Sauron and why others of hire rank have also.  
1st off... I read in a really old book on magik, (I cant remember the name of it) that if some one knows your true name 
it can give them power over you.  So I was thinking that maybe Sauron is not the true name of "big flame eye ball master" and more of a description.  As someone mentioned before... 
	Quote:
	
	
		| "The abominable one or the abhorred one." | 
	
 2nd off... If that is not the case and it is his true name then maybe the Harry potter theory is the key.  Maybe saying his name is just taboo to most beings.  Or maybe speaking the name of sauron brings his attention to you, and I don't think that anyone wanted that, orc, uruk, etc...
but Mos is already in a position of constant contact with Sauron so it wouldn't bother him to speak it, as with good old Witch King.
Now as for my theory as to why he forgot his name:  Maybe he became obsessed with what sauron was teaching him.  Much like Gollum was obsessed with the ring.  I don't know how long it took for Sméagol to forget who he was, but it really doesn't say in the books.  If Mos is described ad still being ambitious and still after his own agenda then it is obvious that he has not been taken over or lost his identity.  I think it was the name that was no longer important to him so he just forgot it.  His attentions were so fixed on the dark knowledge that he was receiving that his old name did not matter, and if everyone around you is calling you The Mouth of Sauron a million times a day for a hundred years I am sure anyone would forget there birth name.  Especially when it holds no relevance. and if no one else could remember his name, then there was no one who would ever call him by his true name to remind him of it.    [img]smilies/evil.gif[/img]