Why did Congressman Joe Wilson need to apologize for calling Obama a liar?

At the weekend I spoke on California talk radio KSFO 560 FM about Lockerbie, Mandelson and other terrible things with one of my favourite hosts Barbara Simpson - aka The Babe In The Bunker. All was going swimmingly until I made the mistake of saying I thought President Obama was a fundamentally decent man, who just happened to have an unusually extensive, sub-Adamms-Family creepfest of disgusting libtard scuzzballs working for his administration.

No one disputed the second part (how could...