Medical evaluations are not based on arbitrary idea's, IE someone is sad/has mood swings and is therefor depressed.
Legally and medically, any sort of diagnosis must be based on empirical data, and if that's not possible, the patient must exhibit or fulfill certain requirements.
In the case of Severe depression, social withdrawal is one such requirement. Contraindication of this, IS a legal reason to invalidate a diagnosis of severe depression, much in the same way someone claiming to have brain cancer, yet has clear CAT scans would have their claim of having brain cancer overturned.
I work with depressed patients all the time, and if one of them told me they went to a party, had a great vacation and went to a strip club with friends, (i recall chipendales being a males strip club), I would medically and legally be unlikely to diagnose her as severely depressed barring some severe indications in another area.