My mother and her siblings are hoarders. From my experience, people suffering from OCD (hoarding, in particular) are very abusive toward anyone who doesn't allow them to hoard. They are also selfish, manipulative and liars. My mother and her siblings are all terrible with finances and you should be pro-active in protecting your parents money. My mother also likes to "hoard" information. If there is a pregnancy, death, illness, holiday invite - anything really, she'll keep it to herself. I think it makes her feel powerful or smart, to know something that no one else knows?
You should set up nanny cam in your parent's house. Good luck. It's a very tough disease to understand.