Why does the liberal media still target mistakes from the Bush administration?

Its' like they(CNN, NBC, CBS, etc.)continue to target the Bush administration to downplay to inadequacies of the Obama administration. If you have ever watched an Obama press conference, when he takes questions he(or anyone in his admin. for that matter)always dodges questions asked by Fox News reporters. Is it because they don't know how to answer RELEVANT questions? To all of you who made fun of the way that George Bush stuttered during his speeches, I hope you listened to Good Ol' B-Rock last night. "Ahhh" and "Ummm" ran rampant through that speech like a bull in a china shop; oddly enough most of that speech was BULL! What do you fine folks think?