That however is an example of an Ad Hominum attack, as is often used in debating, and irrelevant personal attack made to discredit the speaker while completely avoiding the point of his statements. The attack may be correct, but is nevertheless worthless.
A straw man attack, looks at the opponents argument, and rewords it in a way that ignores it's founding reasoning and makes it look weak, then pushes over what they have made. If the opponent is clever he will be able to point out what has been ignored, but often the majority will see it as the actual argument having been toppled. It's hard to pull an example out of thin air, but googling it gave a wikipedia result.
Straw Man