The first is to bring the persons credibility into question. This can be effective and relevant, but only if the person is relying mostly on their own authority to support their case. But if the opinions and positions that are being attacked are supported by something besides the authority of the person being attacked, this is really just a way to avoid the issue, the real arguments. It is an ad hominem fallacy: that if the person is not credible then the position they hold must be false. Even if the person is not credible, if they offer verifiable facts or evidence to support their position their own credibility is of minor importance. Only someone that wants to avoid the arguments and evidence will be pulled into this, duped by it.
The second is to put into question the legitimacy of the rule being broken, usually a moral claim of some sort. Here the real claim (if it is not just a way to whine and complain and there is any logic behind it) is that because one person didn’t follow the rule no one should have to. In the end, this is an avoidance of the real arguments and issues as well. Instead of talking about if the rule is valid at all or in what context it may or may not be, they just try to sweep the whole rule aside. (This is also often done on the back of a false analogy, when a claim is made that one situation is exactly the same as another and don’t bother to argue or acknowledge any nuance or difference.)
In both cases the claim to hypocrisy is used to avoid real issues and a serious debate about the issue at hand. That is why it should always be ignored as the ranting of an idiot full of sound and fury but signifying nothing.
