A decrease in appearance and/or personal hygiene can indicate increased stress or depression. The problem is that it is also a good throw away accusation because it is so subjective. The accuser can simply say that it seemed clear to them that his appearance had deteriorated, and how do you disprove that?
It’s a BS charge.
Plenty of folks aren’t GQ, but that doesn’t make them nuts.
Now if he is wearing his underwear on the outside, that’s a different matter.
BTW. I see some pretty strange dress on folks.
If multiple people confirm a deterioration in personal hygiene, it’s likely to be a legitimate piece of the puzzle. I had a co-worker some years ago who was clearly deteriorating on many fronts, and the decline in personal hygiene was definitely correlated with the increasingly severe depression and some delusions of grandeur. No one ever felt he was dangerous, but he became unable to do any meaningful work, and last I heard was still out on long-term disability due to his mental problems. He was a nice guy, but he just wasn’t coping despite not really having any major stressors in his life. If his psychological make-up had been the sort that’s prone to violence, he could well have gone that route as he lost control of his life.