This morning I heard someone describe Joe Lieberman's speech at the GOP convention as "flat seltzer," which is hilarious and poetically succinct.
Found an earlier citation, too, in a similar spirit:
"Adapted by Howard Korder from his elliptical two-character play of the same name, ''Lip Service'' is a minimalist drama about two local TV personalities who are co-hosts of a dime-store version of ''Today.'' Gil Hutchinson, played by Paul Dooley, is a veteran with the demeanor of Walter Cronkite, but he has about as much pizazz as flat seltzer. His idea of a hot story is a teacher sickout."