You usually won't find good knockoffs -- that is, you probably won't find a bootleg that's intended to look just like the real thing. Instead, what you'll usually find are unauthorized versions that are intended for distribution in certain locales. I've run into DVDs that were apparently based off of the versions distributed by Viz (Ranma 1/2). Chinese subtitling was added and region coding was removed. Also, the Viz logo was removed and there were subtle differences in the cover art. If you can find a good image of the real version, you'll probably spot some differences if what you have is an unauthorized version.