I am not a media analyst but putting my observations as a common man.

First, Newsworthyness of an incident depends on audience. If audience found it interesting, News channel consider it newsworthy. This is decided through TRPs I think.

Second, News channels cant expose ANYTHING. In my country a news can be challenged in court if anyone found it to be unapropriate.

Today all of us are living in a media age. we are loaded with news and information every time. Hot news or breaking news, some are local news, some are sports, some crime and war and that list goes on and on are being broad casted by the news channel. But one can raise a complaint against any such fraud News. One can file a complaint to the News Broadcasters Association (NBA), who will check about any such issue and if found wrong/guilty appropriate action will be taken.

To begin with media or press freedom goes hand in hand with social responsibility, ethical standards, respect for personal privacy, and professionalism. It is possible for any incident to make news or become newsworthy only if it meets the criteria of what is news. It is also important to note that context is a key determinant of what makes an issue news or newsworthy.

For example, a mini (or micro) skirt or a bikini of a woman is not described as indecent when worn in a tennis court for tennis sport, netball game, or at a swimming pool or a beach. In addition, some cultures describe by public kissing or hand-shakes by couples (between males and females) as immoral or indecent activities. News writing skill too can turn a dull subject into a news item.

On the other hand these same activities are cherished by other cultures. The practice of sensational journalism is unethical because good journalism is based on: verification of facts, objectivity, fairness, balanced account, accuracy, truthfulness, competence, and giving the right of reply to the offended person. There should be an exciting news story but not a sensational one.

Privacy should also be within the law and human rights. For example, stealing, murder, violence, child abuse, discrimination, corruption, cheating, or rape can be exposed as crimes in public interest. Some of the issues that define news for the media include: oddity, newness, prominence, controversy, personality, impact, interest, and context among others.

Some of the media errors are not deliberate or intended, like other professions, journalists or editors require more capacity building programmes like education, training, conferences or workshops, and work experience. Many news reporters are still undergoing professional training.

One of the immediate remedies to the offended person is prompt apology or correcting the errors. Many journalists are equally offended by obvious unprofessional outputs by their colleagues that is why ethics is one the courses or course units taught in journalism or mass media courses globally. In most cases news may be defined by the editor or editorial policy of a particular media house.

There is no perfect definition for what is newsworthy, but generally is is things that are new, different or changing.  These judgement are subjective, so the assumption in your question that the news media exposes things that are not newsworthy is not really valid. Different people will have different opinions as to what is newsworthy.  

If the news media discovers wrongdoing and reports it, the news media is not responsible for the ramifications. People who choose to be in the public eye, such as entertainers and politicians, have little privacy because they have PLACED themselves in the public view.

If a politician has to resign because the news media exposes legitimate wrong-doing, it is the politicians fault, not the news media's.  Blaming the media would be a logical fallacy.