The International Obsessive Compulsive Disorder Foundation has tests you can take to determine whether or not you have a hoarding problem. You can find them here, if you're interested in checking into it.
I tend to be a pretty visual person, so the thing that spoke the loudest to me was the Clutter Image Rating. Just scroll down a bit, and you'll find it.
The thing I found interesting was that there wasn't an image 6. Can't tell I have OCD, can you? Ever since I visited the site the first time, I have been thinking about whether or not they purposely left that picture out, or if it was a simple human mistake, and the pictures were numbered incorrectly. I go back and forth between wondering that and wondering, if it's a test. You know. To see, if people pick up on it, and then how many of them obsess over it.
Regardless of my warped thoughts on the whole #6 picture, it gives a really good visual idea of where a person's hoarding might fall on the scale.