Sometimes it's just because they want it gone and don't care if they can get a few bucks for it. 8-10 years ago I was given (by a stranger - Freecycle) A 6 ft. Craftsman work bench with a HEAVY steel frame, and 2" thick solid wood top, a 6" Paramo (Record clone) swivel base vise that looked brand new, a 10" radial arm saw, and a long 6 ton truck floor jack...
The RA saw later went to one of my good friends, as well as the bench. (Also free. I believe in what goes around comes around...)
He claims I'm responsible in some way for most of his major tolls in his shop. (I also got him a 4"planer, a Jig saw and other tools and shop equipment, and other than the DP it's only cost him the gas to come get them...)
He has a Craftsman vise about the size (and style) of that Simplex above, that he got while garage sailing with me for $30... in pristine condition too. it belonged to a model railroader...
He's probably right, I have a 3 wheel band saw I picked up waiting for him, for cheap and a wood lathe for free... (Another Freecycle score)