My favorite type of property to buy is a hoarder home. it may be your favorite too. The trick is how to find them. There's no national list; hoarders are usually hermits, so they may not answer the door, and they may not respond to your mailer.
So how do you find them? I'm asking you to contribute - it's not a rhetorical question! lol
Here's what I'm going to try. I wrote a blog post and started advertising it on Facebook.
http://www.bayareasellmyhome.com/blog/hoarder-house/In general, you need to write a helpful article, try not to be too salesy (I'm guilty sometimes), and create a unique audience in Facebook's power editor that includes any characteristics that a hoarder may have. Over time, Facebook will refine that audience for you and the traffic going back to the article has the second benefit of helping your page rank for those keywords.
Remind me to check back with results!