One reason it doesn't work very well:
[W]hen asked to identify the political leanings of several companies—Coors, Costco, Domino’s Pizza, Whole Foods, Starbucks, Wendy’s, Hilton, and Marriot—few people had a clue. Just 11% of respondents correctly guessed Domino’s Pizza leaned Republican, 10% correctly identified Costco as Democratic-leaning, and fewer than 9% thought Wendy’s was Republican-leaning. Starbucks was the most likely to be correctly identified, with a still-paltry 26% saying it was Democratic-leaning. According to the Center for Responsive Politics, each of these companies or their owners gave more than 90% of their political donations to one party or the other between 2004 and 2008.