It's important to check the back of the manual for definitions of all of the terms in the criteria. Reading the criteria, you may be interpreting them through their conversational meanings. It also underscores the need for doing observed interviews during training, to make sure that you are applying the terms correctly. However, you are right in saying there's always room for improvement.

What's lacking from the psychiatric process is any sort of objectivity in the choice of thresholds distinguishing "normal" from "atypical". The criteria for most disorders apply to huge swaths of the population. They're not symptoms of disease, but symptoms of being human. In order to separate the diseased from the healthy, the psychiatrist must then twiddle nobs to find a distinguishing threshold.

"If you're only annoyed at the shape of your nose, well that's normal. You have a somewhat ugly nose. But, this other chap is really preoccupied with his nose. It's impairing his life quality--- he must be suffering from body dysmorphic disorder. Antidepressants might do the trick!"