Snark is a popular word used for a particular sort of off-putting sarcasm. Snarkiness can manifest itself as adolescent cheap shots, snide condescension, or simple ad hominem patronizing — a sort of “I know you are, but what am I?” schoolyard name-calling. Its incessant use is typically connected with a peevishness born out of juvenile insecurity, and sometimes fed by an embarrassing envy. All politicians are snarky at times; but few obsessively so, given the wages of monotony and insecurity that the snark earns. President Obama is well known both for ad hominem dismissals of his supposed enemies — everyone...