The key ingredient in Breaking the Code of Secrecy is to commit to no longer ignoring the affairs all around us (as the saying goes, "ignoring the elephant in the middle of the room"). So it's important to stop pretending it isn't happening and to speak up and acknowledge your awareness.
However, there's certainly a need to speak up in an effective wayone that has the greatest possibility for having a positive impact with the least possibility of negative personal consequences. (For instance, it's reasonable for someone to consider such practical concerns as the possibility of endangering their livelihood by being too confrontive in a work situation.)
However, this does NOT mean that a person can't speak up and say something in such situations. There are some guidelines that can help anyone struggling to determine how to handle something like this in the most responsible/effective way. One of the first issues is getting clear about Who, Why and How to Confront.
For instance, the specific question above, "Is it appropriate to approach a doctor who is carrying on an affair and let him know that this is wrong?" illustrates two serious problems. First, it's not appropriate to confront someone (other than a personal friend with whom you have a close relationship) with your personal opinion/judgment that their behavior is "wrong." It's simply not reasonable or effective to lecture co-workers about not meeting your personal standards of behavior.
The statement that a person makes needs to be about themselvesnot about the other person. For instance, it's appropriate to say, "I feel uncomfortable with (or distracted by or uneasy about) working in an environment where affairs take place. I know I don't have the right to tell you what you should do; but I thought I should tell you how I feel and that I would not in any way "cover" for the affairs or "cooperate" in maintaining the secrecy about them."
Many people experience ambivalence and frustration at being expected to "cooperate" in the deception of affairs, especially if they see no reasonable way to avoid it. One of the most difficult situations is when people are expected to "cover" for co-workers. (For instance, secretaries invariably know a lot about the private lives of those for whom they work, and they are routinely called upon to help protect an affair. I know about this from first-hand experience as an executive secretary many years ago.)
Work-related affairs are extremely common, and they have an impact on many aspects of getting the job done. The concerns may cover a wide range of other issues: the amount of time an affair might take from a focus on business, special treatment or privileges that might accompany an affair, unfair distribution of labor by virtue of time spent on an affair, or just being distracted by an affair. So, to return to the reasons/motives in "speaking up," these are legitimate (and potentially effectiveness points to make), not just saying it's "wrong."
The way in which your comments are received (and any potential positive impact) will rest in large part on the spirit in which the comments are offered. While there may still be some negative reaction at your speaking up, any approach other than the one described above will almost certainly do no goodand is likely to result in anger at your interference in something they see as none of your business. In other words, any effort to discuss this matter should neither be self-serving nor self-righteous. The effectiveness of anything that is said will be determined by the attitude with which it's approached.
The bottom line is that for someone like the writer of this question who feels uncomfortable in such a situation, there's no simple solution; each person must make their own decision about how to react. "After the fact" like the above situation, it's much more difficult to determine the best course of action. With more awareness about the impact of so much secrecy, we may be better prepared to face these situations and make a conscious decision as to how we plan to handle them.
For more information about affairs at work, see: Sex in the Office.
P.S. Regarding the questions chosen for Response: