We make sure that all of the ads we run are attached directly to the candidate and to the campaign. If they're publicly espousing something that other people might take issue with, they can take it up particularly with that campaign. To your specific question as to how I would know whether it's misinformation versus just being negative, my response is that sometimes negative advertising is simply pointing out the truth about that person.
I can think of specific advertising. It was an ad saying look at what this person has done. Once you clicked on the ad, it brought you to a website. We didn't control the website, though it had factual information on it about some of the things that the particular candidate had done in the past that people might find unsavoury. That was negative advertising, but it also appeared to be correct.