Being elected to serve a constituency, serving the people's best interests should be considered an honor. Earning a vote is the equivalent of earning trust which is the reason when an elected official engages in unethical, dishonest, or illegal behavior their ability to make good sound judgments is immediately placed in question. As it should be. Should engaging in this kind of behavior be grounds for resignation?
While we the people should not be so naive as to expect our elected officials to be infallible, we should expect that when they take the oath of office they clearly understand the set of moral, legal, and ethical obligations that come with it. Just as one takes responsibility for accomplishments, one must take responsibility for failures and this means when an elected official engages in irresponsible, inappropriate or questionable behavior, he or she must put their own personal ambitions and goals aside and resign.Once the people's trust is breached, it cannot be repaired. The resignation indicates that elected official accepts the responsibility for his/her mistakes and respects the office enough to honor and maintain the integrity of that office.
Serving in public office is voluntary, not mandatory and any individual who does not feel up to the task of accepting the obligations of public office should either step down or better yet, not run at all. Of course there are those who find it difficult to relinquish the power, but how soon they forget that the seat does not belong to the individual, it belongs to the people. As such the people have a right to demand their elected representative exhibit the characteristics of leadership which includes among other things, personal ethics, trustworthiness, and competency.
The individual who cannot meet these standards need not apply.