Dang, you guys are paranoid.
I was a Peace Corps volunteer, and when I finished my service my soon-to-be-wife and I traveled across the US, staying with friends, friends of friends, and in random places that turned up for whatever reason. 8 weeks, 12,000 miles, and we didn't pay for a hotel room ONCE. (We did pay for a Golden Eagle pass, which allowed us to camp for free in a lot of national parks, but that didn't really become useful until we got west of the Rockies.)
People are (by and large) nice. Treat them well, they'll treat you well. I'm amazed this service hasn't popped up before now.