As of February 2012, Voters are still in the dark in Maine regarding who financed a 2009 campaign that reversed the rights of gays to marry. Despite two Federal Court decisions upholding Maine's disclosure laws, attorney Bopp on the behalf of National Organization for Marriage vowed to immediately appeal a January 31st, 2012 ruling against his client to the US Supreme Court so donors can remain anonymous. 
Of the two US Circuit Court of Appeal rulings, it is the second one in Boston that perhaps contains the seeds of doing for PACs that accepted big contributions. In National Organization For Marriage v. Walter McKee (Maine), the Court included an interesting topic:
"Funds that can reasonably be determined to have been provided by the contributor for the purpose of initiating or influencing a campaign when viewed in the context of the contribution and the recipient's activities regarding a campaign"
From this opinion, and based upon how the press and press from the PACs themselves, a reasonable person would conclude monies donated to a specific PAC will be earmarked to promote a specific candidate or cause. This in turn means most monies directed towards these PACs are essentially monies directed towards the candidates themselves.
The second edge of the legal sword available to those harmed by spending, now up as much as 1600% for 2012, is to contest anonymous donors and PACs working towards specific candidates that have resulted in past elections and ballots initiatives. Even before an election takes place formal complaints can be filed against clients depending on circumstances. For example Louisiana law states "Anonymous contributions must be transmitted to the State.....Violations of the Campaign Finance Disclosure Act by a PAC can subject the chairman and treasurer of the PAC to civil penalties of up to $10,000." An example of a complaint like this occurred in Minnesota in the 2012 election cycle over groups spending millions of dollars to promote an amendment to the state constitution to ban same-sex marriage. There, a national gay rights group demanded the Minnesota Campaign Finance and Public Disclosure Board to investigate the disclosure reports. "This is part of (the National Organization for Marriage's) systematic attempt across the country to oppose public disclosure and hide its donors," Human Rights Campaign President Joe Solomonese said in a statement. 
This has opened the possibility that the most effective use of campaign workers is to stop an opposing side from using money against it. All that is required is to audit and file complaints when an organization directly or or indirectly benefits from spending exceeding individual limits or if it came from hidden donors.
Further, Pandora's box may be open should election boards step in, with possible court order, to invalidate voter results when extensive amounts of anonymous PAC monies were illegally used to sway voters.