Corporate dollars and political campaigns are like oil and water for well-established retail brands.

Despite the troubling flexibility provided by the Supreme Court case Citizens United, which allowed more direct corporate and union contributions to political campaigns, this freedom can be perilous.

Target learned first-hand how political donations could damage its brand. A public relations disaster followed its contribution to a group backing Tom Emmer, a Republican candidate for Governor in Minnesota, where Target Corp. is based.

According to a study by Brandweek, a trade publication, Target’s reputation was hurt in early August when the donation was revealed — and still hasn’t recovered. The publication’s BrandIndex report showed the company lost one-third of its “buzz” score in 10 days last month, recovered modestly, then fell again during a media backlash. Target’s stock price fell to under $51 a share by Aug. 30, but has since recovered to close above $53 recently.

Not only did the contribution result in a blizzard of op-eds, blogs and negative publicity, it seeded a boycott campaign from the well-funded progressive organization MoveOn PAC.