Ips tend to be the worst because they're usually focusing on what others are doing rather than on what they themselves are doing, and although they tend to be critical of everyone in general, they often see criticisms of themselves as nothing more than personal attacks that require immediate parries or escapes. Ejs are somewhat better because they tend to listen to the other's point of view a little more while they're fighting to prove the other wrong. Eps focus more on what's out there rather than what's inside but they do tend to be objective on the rare occasions when they do focus on what they're doing (or often "not doing"). Ijs are usually quite good a knowing themselves but many do not like what they see; obliviousness can have it's advantages.

a.k.a. I/O