Watch out for that sweet-talker—he's great at convincing people to spend money.

sweet-talker 是由形容词 sweet（甜的）和名词 talk（谈话）组成的复合名词，加上后缀 -er 表示"做...的人"。sweet-talk 本身指"用甜言蜜语哄骗"，因此 sweet-talker 指"擅长用甜言蜜语哄骗他人的人"。