Need Exorcism? Symptoms Here

From (of all places) Time magazine.

Q) So how is a priest supposed to figure out that an exorcism is warranted? How do they judge who is and who isn't a worthy candidate?

A) The ritual stipulates that there are three signs that the priest has to look for: abnormal strength, the ability to understand unknown languages and the knowledge of hidden things. But they're very arbitrary, even those things. So they have to be in concert with something else. And typically what priests look for is what they call the aversion to the sacred, which is a person's inability to pray, to say the name of Jesus or Mary, to even look at the priest. Typically, when the person comes to see them, it's the last thing they want to do. They tend to have gone to see many doctors in search of a medical cure for whatever is afflicting them. They don't believe that the problem is demonic.

Interesting and concise.

...usually, the more dramatic cases deal with people who are screaming, using their voice, shoving and punching, getting up, smacking their head against the wall — just very violent...

Well, that takes in a lot of LeftOWackies and high school kids (but I repeat myself.)

HT: CMR