If the DNC wants to spread a lie, one of the more efficient ways to do it which will damage their opponent where he needs his support, is to feed the right information crafted to look like something they want to hear. Since many rightwingers dislike Powell, it is easy to attribute these kinds of quotes to Powell since the rightwing's anti-Powell side wants so desperately to believe he's a bad guy that they will believe anything they are told, however improbable, which makes Powell look bad- even if it also makes Bush look bad. Thus the right is used to spread the information to other people on the right side of the aisles who wouldn't accept the information if it came directly from the lib source.