Ehh, for now, I would take Tobi's statements with a grain of salt, we have seen he has said things to skew things in his favor.I got that point from Obito's statementYou must be registered for see links
The only statements I have seen about the state of the Juubi's chakra from a reputable source is here..
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Naruto states that the "bad" chakra of the Mazou disappeared and the Kyuubi even states that the Juubi has no "feelings or ideals". Obviously, the Juubi is natural chakra and that is why Naruto was able to hit Obito. I think that was made apparent last chapter. But to say the Juubi has some type of foul chakra, at this moment, and that Naruto has some equal but opposite chakra I think would be stretching it. They both use Natual Chakra. Lets just leave it at that until we hear otherwise..