No random Craigslist clown is coming into the house where my wife sleeps, even if I escorted them in with a gun to their head because they could scope it out and come back later. I said I'd record a video of it working and send that over. No more replies. :)
Worst case, I would probably have it in the garage and they can look at it there. Probably a risk you have to take to have someone cart off a big old treadmill.
One thing I would definitely do is probably sell it fairly cheap. Just to make sure it moves with the 1st person who is interested. Rather than get a bunch of time online and gazers coming over. People are also less likely to complain about something if they get a deal on it too so it's a win/win. Well other than the cash lost but I'd make that deal.
[0]http://www.tractorsupply.com/tsc/product/carry-on-trailer-me...
One other thought is to use a more localized service like Nextdoor where you are only selling to people in your subdivision/neighborhood. I would think this would cut down on the riff raff, but also cuts down on potential buyers.