While in college, I had a guy that wanted to crash at my place for a weekend. A week later my wife told me to give him the boot. As he was leaving I noticed that he seemed to have more stuff than what he moved in with. We had a tense standoff where I told him I wanted to look in the boxes before he could leave with them, while he is yelling and cursing at me about not trusting him.
It turned out that he had ransacked lots of small valuables (my wife's jewelry), and a large number of collectible LPs (rare autographed editions, etc). The strange thing is that I felt bad about not trusting him, but in the end I was glad to get my shit back and be rid of him.
Stealing from someone that opens their home to you is about as low as a person can go.
ADG