True hoarding behavior is actually fairly common, with anywhere from 2 to 5 percent of the general American population meeting diagnosis requirements [source: WebMD]. Before you self-diagnose, we're not just talking about someone with a few hundred CDs lying around. Instead, clinical hoarding behavior is characterized by the person's inability to function or move about in his own home.
For example, he can't use his kitchen to cook meals or even reach the bathroom for its intended purpose. As you can imagine, it's not healthy for anyone to live like that, particularly when many hoarders are emotionally attached to actual garbage, often feeling racked with guilt over disposing of something they perceive as important. Many times, neighbors become wise to the situation before anyone else, since pests and odors become unavoidable.