The American Idol auditions prove that there are several different types of bad singers. Some people have pitch problems, but they at least get close enough to the notes that you can recognize the melody. If they were shooting a BB gun, they would shoot at the bullseye but hit one of the outer rings.
Then there are the people who completely miss; they don't even get within a half step of the pitch. If they didn't sing the words, you would never be able to tell what song it was supposed to be. These are the ones who not only miss the bullseye, but put a hole in the neighbor's window at a 90 degree angle to the target.
You can tell a lot about the contestants before they start to sing, just by what they say before the audition starts. Good singers are realistic. They know that they are good, but they have heard a lot of other good singers out there too. They usually talk about preparation and trying to do their best. They have probably auditioned for singing parts many times before. They know that you can be good, but still not be what the judges are looking for.
It's usually the truly bad singers who are convinced they are a sure thing, because they are delusional. And if they are completely confused about one thing, they are usually wrong about everything else, too. So when unattractive people describe themselves as super sexy, they usually aren't good at singing either. It's part of a general pattern of not being realistic about themselves.
It is an especially bad sign when they boast about how "different" or "unique" they are. Hey, if you are nothing like any famous singer, guess what? It is usually because you are an awful singer. It's usually not because you have an incredibly beautiful type of singing that nobody else has ever tried before.
The biggest surprise for me this season is Paula Abdul. I'm really liking Paula so far this season. Last year I thought her odd behavior and speech patterns probably indicated that she was drunk. This year she seems alert, on the ball, and charming. Maybe she was just trying to be funny before.