how does a hoarder rationalize it?

I might have some insight into this, considering that I live with one.

The wife is the hoarder, the husband is my best friend, I'm the roommate. Two days ago the husband decided that he wanted to actually cook for a change instead of eating instant meals and fast food, so he cleaned the kitchen. Previously, the only counter space in the entire kitchen was this little one foot by one foot square between the sink and the coffee maker, so one of the first priorities was to clear all the clutter off the counters. The kitchen is the cleanest it's ever been. It's wonderful, I've been cooking non-stop.

This morning while I was making breakfast the wife was going absolutely apeshit about the kitchen. Part of her rant was a constant stream of abuse against herself, stuff like "I'm just the worst person in the world, huh!?" She was saying this to no one in particular, and none of it was prompted by anything we said, she was just throwing a spontaneous pity party.

Now, think about this for a second. How many people do you know who would get angry that their spouse cleaned the kitchen? In most of the relationships I've been in, that may as well be foreplay because it usually leads to sex. Not with her. Somehow or another it makes her extremely uncomfortable, like she'd rather just live in filth than have somebody else clean up after her.

I don't completely have my head wrapped around the issue, but it's pretty clear to me that there is a cycle of guilt and shame associated with hoarding behavior. She spent the entire morning making herself miserable, as if she had to make up some sort of deficit because we weren't punishing her for it.