Yes, it is. Kerik's unsavory background was known to some of us long before he pleaded guilty last week to a number of criminal counts related to graft and corruption. A person in a position of authority can't hire a slimy, corrupt greaseball to a high-profile public position and then step away and pretend that the actions of said slimy, corrupt greaseball shouldn't reflect poorly on the person who appointed him.
The fact that Kerik was named police commissioner after serving as Giuliani's personal driver is all you really need to know.
But he have had our share of corrupt oficials. We just had a Republican congressman, "Duke" Cunningham, put in jail for corruption, and currently the Republican governor of Ohio, Bob Taft is mirred in corruption even as we speak.
And neither one of these guys could be re-elected today. If they were Democrats, they'd be front-runners for their party's nomination by a wide margin.