The “Mad Men” are getting very angry indeed. In response to the sharp economic downturn, ad firms are now trying to tap into new, fearful zeitgeist, with messages crafted to appeal to aggrieved consumers. “Progress is overrated,” declares one cereal company. Jet Blue, the US airway, has a new series of commercials mocking corporate bigwigs who must now fly with the rest of the plebes. “Candor is in,” declares one ad exec.