Sure, your husband’s habit of brushing his teeth five times a day is a little weird, but is it an actual personality disorder? Maybe, maybe not. The key to knowing if a strange habit is a diagnosable “disordered behavior” lies in a few criteria: 1. The behavior is inflexible, no matter what situation the person’s in. 2. It disrupts their work or social life. 3. It’s not part of another mental disorder. And 4. It’s not caused by a medical condition, drug or medication. If you’re all-clear on those points, it’s likely just one of those kooky behaviors everyone has in some way—and yes, a huge waste of toothpaste.