I exist to sit in water, but you’ll panic if any gets in.

I am dirty when you're clean, I get wet as you dry.

For some I'm a breakfast delight. Cooked, baked or cold overnight. But not everyone loves me as such. Especially children hate my guts.

Tear me off and scratch my head, what once was red is black instead

Not a letter, but you can use it to spell HORSE. Not a gun or a camera, but you can shoot it. Despite its name, Longaberger had nothing to do with it.