I think they are far too concerned with defending themselves and "winning" the argument to bother with whether they are being hypocritical or not. And they are so convinced they are right and justified, that they aren't about to go over what they said and second guess themselves, later. It's a vicious cycle.
I like how SIP uses "ad hominem" as an ad hominem attack, LOL. XD And by "like" I mean find lulzy due to the ridiculous irony of it.