To what extent are you "entitled" to "investigate" into the personal lives of journalists and public critics?

If your goal is not to intimidate, what purpose does it serve and accomplish? Freedom of the press is important and is part of the Constitution. Journalists can investigate a business even if you think they shouldn't.

Looking into the financial ties of journalism is game. But the industry and business of journalism is not the same as someone's personal life, their sexual preferences, children, family, etc.