Politicians soiled by corruption and apparent corruption win all the time. Their sketchy activity often helps them. Last election, Harry Reid and Lisa Murkowski were reelected to the Senate, for instance.

Often, though, the taint of corruption brings down politicians. Democratic Rep. William Jefferson lost an overwhelmingly Democratic seat in New Orleans in 2008. Dan Rostenkowski lost in Chicago in 1994. Ted Stevens lost in Alaska in 2008.

This year, there are two competitive races where one candidate is under the shadow of ethics problems.

Shelley Berkley, Democrat of Nevada may have abused her power in order to help her husband’s business. As Politico described it:

Berkley used her office to aid her husband’s kidney transplant practice in Las Vegas. Federal regulators were looking to shut down the kidney center at University Medical Center in Las Vegas in 2008, concerned about the high failure rate among kidney recipients there. After Berkley’s intervention, the contract was extended.

Berkley is challenging appointive Conservative Republican Dean Heller, who took the seat after Republican John Ensign resigned in the wake of his affair-and-trying-to-buy-off-his-chief-of-staff-with-whose-wife-Ensign-was-sleeping scandal.

In Miami and the Florida Keys sits the most ethically troubled Republican congressman — Freshman David Rivera. Democrat Joe Garcia is running against Rivera again.