I've seen similar shows to that. I totally understand that it's a mental issue. My ex's parents are hoarders and when I was dating my ex, we'd go over there and his mom would say that the mess around their place was my ex's and his brother's fault. Considering that my ex lived with me, and his brother lived with his gf. :/
I dated my ex for 5 years and I recalled twice a year, that my ex and I would be called out to come and "help" clean up / organize the place so that it was ready for some sort of big family dinner (Thanksgivings or Christmas)
My ex said that he finds it disgusting going over there now and him and his gf have tried to talk to his parents about it but they always have some kind of excuse for the state of their place.