One technique for finding companies that are trading below their intrinsic values is to look at clean companies within tarnished industries. I did this last November during the height of the mutual fund scandal, when companies such as Janus (NYSE:JNS) and -- well, well, well -- Marsh & McLennan (NYSE:MMC) were being keelhauled for their alleged misdeeds.

You remember the headlines, don't you? By and large they weren't "Putnam Scandal," or "Bad Things at Janus," but rather "Mutual Fund Disgrace" writ large. And this was largely correct -- a large number of funds were found to be behaving quite badly. Ah, but not all of them. Interestingly, though the named characters saw their stocks sell off the worst, almost no mutual fund company skated through last November and December without some decline in share price. Even the ones that had nothing to do with the scandal took it on the chin. At the time, I identified three companies that had been hit and were (as far as we knew) clean as a whistle: T. Rowe Price (NASDAQ:TROW), Motley Fool Stock Advisor selection Affiliated Managers (NYSE:AMG), and Franklin Resources (NYSE:BEN).

How'd that work out? Not so bad -- T. Rowe is up 46%, and Franklin Resources is up 41%. Only Affiliated has swooned, down 7% at the moment. Meanwhile, Janus sits up 14%, while MarshMac -- well, you know all about them I'd imagine.

The same thing happened with companies that are in the insurance sector but seem unlikely to be deeply involved in the ongoing hydra-headed insurance scandals, again centered upon MarshMac. One such company is health benefit plan provider UnitedHealth Group (NYSE:UNH). A few weeks back, New York Attorney General Eliot Spitzer let it be known that his investigation, centered on the contingent commissions paid to MarshMac, was actually the tip of a scandal that touched nearly every single sector of the insurance industry. This is a superior business whose stock has enjoyed superior returns over the last few years, but investors are suddenly nervous now that rivals Aetna (NYSE:AET) and Cigna (NYSE:CI) have been served with subpoenas. But UnitedHealth? Nothing, though that didn't stop the analysts from downgrading, just in case.

What's happened since then? The company's shares have risen about 28% in the course of a month. The insurance investigation is apparently just getting under way, so it is of course possible that there may be another dip in UnitedHealth's future. But like the asset managers listed above, this is a company that is renowned for its conservatism in accounting and in practice. Shares were priced as if the company were complicit in wrongdoing, where if past behavior is any indication (and it should be counted on as an indication, not proof positive), this actually seems somewhat unlikely.

UnitedHealth, like Franklin, T. Rowe, and Affiliated Managers, is a rose sitting squarely in the midst of pig slop. It just may get splashed again, so get ready.

Bill Mann owns none of the companies mentioned in this article. UnitedHealth has been a multiple-occasion selection in the Motley Fool Stock Advisor . Check it out for six months, without risk. No Huns will come to your house, I promise.