I am just now starting to come up to speed on the Ani DiFranco / plantation retreat thing, but...
If somebody says that a given person's slaves were "probably well treated for the time", and the insidious depravity of that statement doesn't immediately thump you on the head, perhaps this quote will help put it in perspective:
The cells of the Inquisition were, as a rule, large, airy, clean and with good windows admitting the sun. They were, in those respects, far superior to the civil prisons of that day.
That from the 1911 Encyclopedia Britannica's article on Thomas Torquemada[trigger warning].