My position is that Sauron did not allow his servants to use any personal name for him under normal circumstances, probably due to a desire to be as impersonal to his minions as possible, befitting the "king and god" status he wanted to have with them.
When dealing with his enemies, however, the use of a name was required. The Mouth wasn't the first one to do it apparently, either.
Quote:
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'Then about a year ago a messenger came to Dáin, but not from Moria--from Mordor: a horseman in the night, who called Dáin to his gate. The Lord Sauron the Great, so he said, wished for our friendship.'
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That was Glóin speaking to the Council of Elrond.
So, when Sauron dealt with those he didn't command, he had to use a name, and I think 'the abhorred' was probably not something he particularly hated; on the contrary, he would likely have been proud of it.