American Politics is a minefield. Are interview questions bought? Does an interviewers political opinion ever get in the way in a mainstream broadcast? Hard to say. The Clinton Foundation, presumably, is a charity. It is, by it's nature, political. Should that stop people, even journalists, giving up time and resources to support it? I say no.
Cheryl Mills conducting interviews for the Clinton Foundation while working as chief of staff may not have been the best thing, I'm not sure what if any negative effects it on the US itself. It's worth noting that that Justice Department looked into allegations surrounding the foundation and didn't find anything worthy of opening an investigation. It's also worth noting that there's probably some crappy political backroom dealing and some people using their positions or the foundation itself for personal gain, but I'm not sure about the conflict of interest.
Some might claim that Cheryl Mills was violating ethics rules when she interviewed people on behalf of the Clinton Foundation while working in the government in the State Department. However, a crucial detail in this story is that Mills was interviewing people as a volunteer. She was not receiving compensation from the Clinton Foundation for performing these interviews, which would likely exonerate her from any ethics violation claims. If she were receiving payment from the Clinton Foundation, it would have been a clear and direct violation of ethics.
I'm not sure why there is this witch hunt against the Clintons that has gone on for decades. The Republicans want to win the White House at all cost, even if it means putting this crazy, hate spewing man in there. There are now others like "unknown" hackers who all of a sudden just in time for the election have broken into the DNC and stolen emails that are now being used against Hillary Clinton's campaign. Number one they are ill gotten emails and should not be released to the public or the news media should be banned from using them because a crime was committed. Someone really wants Donald Trump in the White House. I wonder why.