they are usually copies of the Song of the South Laserdisc, so they are in no way close to what a real DVD copy would look like. Unfortunately they are also technically illegal to buy.
There is a nice section of SotS on the second disc of the Alice in Wonderland Masterpiece Collection DVD, in the "One Hour in Wonderland" program. It shows the full Zip-a-dee-Doo-Dah number and one of the Br'er Rabbit stories. The video quality is quite nice there too.
I read that Scott (?) McQueen the former head of restoration at Disney did a full restoration of the film a few years ago, so it would be ready for DVD release as soon as someone has enough cajones to pull the trigger on it.
You'd think they'd just quietly put it out there, as a limited edition or as part of a Treasures package, just to undercut Universal and the Bootleggers.
I, too, don't see a big problem with it - it seems like most people are not even upset by the stereotypical voices, etc, of the cartoons, but more the fact that the Freedmen are happy and singing, when, really, their lives stunk and they should have been depressed and miserable.
If you look at the way Brer Fox, Rabbit, and Bear behave/talk, the characters don't seem to be any more offensive/stereotypical than the dinner table scenes in the Eddie Murphy "Nutty Professor" movies, and if I recall, all the characters were voice by African Americans, so it's not like it was a white man charicaturing a black man's voice.
Most other movies that are that age or older are celebrated for the innovative film making that they were and use the controversial nature of their content as a jumping off point for discussions on how far we have come. While Song of the South in no way compares to "Birth of a Nation" in terms of racially inflamatory content, "Nation" is widely available (and shown every year during black history month on my campus) while the only way to see Song of the South is by buying a bootleg with Chinese subtitles from Hong Kong. SotS and Birth of a Nation can both be considered ground breaking cinemating achievements, from a pure technical film making stand point. They should both be available for the public to see.