The things that usually kill my interest in anime are repetition and certain people.
Sometimes I get really annoyed by the same old tired character and genre stereotypes and those really make me not want to watch any anime when I keep running into that.
On the other hand though, shows like
Wolf's Rain and the new
Ghost in the Shell : Stand Alone Complex series let me keep faith that there is really good and original work coming out.
The second thing would be people. Like a casual friend of mine is always trying to get me to watch absolutely everything new that he gets and usually 75% of it is trash, because he just likes anime for being anime (if that makes sense to people).
That's not to say that I don't like anime anymore though, there're just certain factors that try my patience with it.
