There is some degree of subjectivity involved in knowing when it is appropriate to blow the whistle in the business world. There is not exact way to determine when it is right to do so. My own view is that it is appropriate to blow the whistle when a firm is doing something that will clearly harm innocent people. It is not appropriate to blow the whistle simply because you disagree with what a firm is doing.
When a firm is hurting people who should not be hurt, it is right to blow the whistle. For example, if a restaurant chain is intentionally giving poor service to non-white customers, it is harming innocent people and should be exposed. Similarly, if a firm is disposing of toxic waste in a way that will poison people in the community, it should be exposed. These are times when it is right to blow the whistle.
However, it is not right to blow the whistle if the firm is simply acting in ways that you personally do not like. (Actually, it is your right to blow the whistle in such cases, but you should not be protected if your firm decides to fire you for speaking out.) For example, if you work for a fast food chain and you do not like the fact that its executives have decided not to post nutritional information on its menus, you should not feel that you have the right to blow the whistle with impunity.
There is a lot of gray area in this definition, but this is the general distinction between times when whistle-blowing is and is not appropriate.