Editors — regardless of their political leanings — know that plurality mismatches are a sign of bad writing (which, in turn, is a sign of sloppy thinking). The conservative who wrote this eight-word bumper sticker included two glaring plurality mismatches:
Multiple liberals have multiple mouths, and multiple conservatives have multiple brains (dusty, rusty, and under-used, in the main, but every conservative does have a collection of soft tissue, axons, neurons, and synapses known as a brain in his or her cranium). Thus, to be grammatically correct (not factually correct, that’s another matter*), the author of this bumper sticker needs to replace mouth with mouths and brain with brains.
*This criticism focuses strictly on the writing errors in this bumper sticker; I could easily write a separate post listing dozens of examples that disprove this grammatically challenged assertion.