bad·mouth or bad-mouth
tr.v. Informal bad·mouthed, bad·mouth·ing, bad·mouths
To criticize or disparage, often spitefully or unfairly: "those cross-Atlantic aficionados who persistently idolize the British theater and bad-mouth Broadway" (Benedict Nightingale).
批评或毁谤，通常怀有恶意或有失公平：“那些穿越大西洋的狂热爱好者一直都崇拜英国戏剧却恶意批评百老汇音乐剧”