As someone with a hearing loss, I have a particular bias when it comes to seeing characters portrayed with some kind of auditory disability. I have considered writing one before, and I know just how I would do it, but I have never really gotten to the point of wanting to. Probably because for me, RP is an escapist mechanism, and escaping into a character without a disability can be just as much of a refuge as escaping to a fantasy world or science fiction. 

That said, I have seen disabled characters played well. One has to be careful not to blatantly offend those who might have those experiences, but it's also important to remember that there is still much discrimination and sometimes even hatred towards disabled persons still in our world. How that translates into the RP world depends on who is writing, and what the setting is, but the most successful characters with disabilities have always been those (for me, anyway) who tell the story of how they cope with an abled society right along with the rest of the RP's events. 

It's also important to craft a character with a disability that fits the RP. Certain settings are going to make for poor quality RP if one's character has no way to move about, see, speak, hear/process language, read, or has a different set of social behaviors. In some cases, it may not be realistic to see a certain disability in a public character, those who did live in certain eras of history were shunned or hidden, or even left to die in infancy. If it's a modern day or future setting, the sky may be the limit, but for fantasy or historical settings you should be careful that your character will have ample RP opportunities.