I don't mind. As long as he doesn't start talking trash about his opponents or harms people other than himself, it's his business. If you can't handle it, don't watch. Really simple.
Well it can be a kind of insulting when someone is playing a very tight match against him and he goes on whining how sick he is and how bad he is playing. Essentially stating you are so bad compared to me I only lose a set to you when I am sick and playing very bad. Disgusting I think.