The question is whether corruption is always morally/ethically wrong.
To set up the premise, let me start with some examples. In third world countries (I'm from one myself, so I can speak from experience) many people, who live below poverty line, can only earn some living by means of corruption. There can be many examples of this but here's one: say, in certain areas of some city street vending is not allowed, but the vendors, ignoring such regulations anyway. Or they may sometime do it without going through the hassle of obtaining bureaucratic permission. This may not be a perfect example but this does show the point that breaking rules and regulations on a systemic scale (if we can call that corruption) for mere livelihood. Maybe a better example yet are those of the low ranking bureaucrats themselves who are generally prone to bribery because their work does not pay them much. Another example might be that of the people, who are poor, not ever buying train tickets while travelling and undertaking all sorts of measure to avoid being caught by the ticket checkers. Third worlds can be full of these minute corruptions, and the first world countries (never being in one) I can only guess, there might also be some sort of corruptions as well up to certain extent. (I didn't have to say this, but, I'll: I am not suggesting that 'all poor people are corrupt' neither I am suggesting that 'only poverty is the causal agent for corruption')
Now, there I believe can be two perspectives on this: a) teleological and b) deontological. A teleological perspective may say at the end the people, who otherwise wouldn't be able to make a living, is being able to thus it is not wrong. A deontological perspective would, of course, object to the wrongness of the acts themselves without worrying about what happens to those people if they follow the 'right' set of regulations set for them by the other well-meaning members of their society.
A naïve utilitarian thinking may lead us to think that such minute corruptions are ultimately doing 'good' for a greater number of people (as there are more people below the poverty line in a third world country) and therefore, those acts are not morally and by that extension not legally wrong (as if I remember correctly, Bentham, indeed though with some flaws, later to be objected by Mills and other, developing the utilitarian principle as a legal doctrine rather than as a moral doctrine per se). However, it is arguable that such commonplace occurrence of corruption and nobody's willingness to do something about it, if becomes 'habit' of the population or if the population forgets to call out corruption for what it is, may lead to a snowball-like effect and every strata of the society and bureaucracy may replete with corruption, as is the case for many third world countries. Thus, allowing such minute corruptions would do more harm than good and therefore such corruptions are morally wrong.
Another thought is that if corruption is a natural tendency of a human living in an 'unfair' society can it be justified to hold people morally culpable who lives on the 'unfair' extremes of our society, i.e., does a broken society gets to hold people responsible for their corruption if the act itself is prompted by the brokenness of the society itself (yes, I am considering poverty as the 'brokenness' of the societies).
I would like to hear other thoughts and criticisms. Thank you.