If a person's history is to cheat in business, it might be that the person habitually and easily lies whenever on the phone and he or she can't see who is on the other end. The person might be solidly in the middle of the bell curve for everything but predilection to dehumanization. (Scholarship FTW.)
Alternatively, the person might have a unique situation, such as being blind, isolated, and requiring a reader to speak out received emails in Stephen-Hawking voice, that is such that anyone would experience dehumanization sufficient to make them cheaters. (I'm not claiming this is the case, just that some of similarly plausible set-ups would cause actions, just as time since judges ate affects sentencing.)
So either virtue ethics breaks down as people's uniqueness lies in their responses to biases and/or people's being overwhelmingly, chaotically directed by features of their environments.
Either way, cheaters and thieves are likely to cheat or steal again.
If I can look someone in the face, can usually detect lying. Voice only, can often detect lying. Text only, can sometimes detect lying.
Thus if a person is honest in proportion to the bandwidth, this requires no more psychological explanation than the fact that burglars are apt to burgle at night.
Recently I summarized Joshua Greene's attempt to 'explain away' deontological ethics by revealing the cognitive algorithms that generate deontological judgments and showing that the causes of our deontological judgments are inconsistent with normative principles we would endorse.
Mark Alfano has recently done the same thing with virtue ethics (which generally requires a fairly robust theory of character trait possession) in his March 2011 article on the topic:
An overview of the 'situationist' attack on character trait possession can be found in Doris' book Lack of Character.