Turn off Fox and MSNBC, and check to see who's funding a candidate's campaign coffers. If Americans did those two simple things more often, we'd be a lot better off.
That can be helpful, but the result of Citizens United
is that outside entities can spend as much money as they like for or against a candidate as long as they aren't explicitly coordinating with a candidate in the race. This is a joke because it isn't practical to constantly monitor covert communications to discover coordinating efforts and because the law is easily skirted via technicalities (candidate C announces at a press conference the importance of pointing out the flaws in his opponent's tax policy, after which all the outside groups subsequently begin beating that drum, though no communications were shared between staff members).
SuperPAC's require a name and address for each donor which they subsequently report to the FEC, but does anyone think the FEC is verifying all of the data they've been handed? Further, people can donate via a corporation or LLC, and if it's got unclear ownership structure, the identity of the donor is obscured. Finally, due to some IRS law or other, any group can from a non-profit wing and take unlimited anonymous
donations as long as only half the money is spent on politics and as long as that which is spent counts as "issue advocacy."
I don't know how likely it is, but for all we know Al Qaeda, foreign governments, and other undesirable elements could help fund an American campaign if they really wanted to.