口くちがうまい

く

ち

が

う

ま

い

JLPTN2

Meanings

1

expression, i-adjective

Describes someone who speaks in a flattering, persuasive, or superficially charming way, often with a negative connotation of insincerity.

口くちがうまい人ひとほど、信しん用ようできないこともある。

Sometimes the more glib a person is, the less trustworthy they can be.

口くちがうまい
Most common spelling; uses kana for うまい to avoid kanji ambiguity.
口くちが上手うまい
Kanji spelling for うまい; less common but still used.
口くちが巧うまい
Rare kanji variant; 巧い can imply skillful, but this spelling is seldom seen.

口くちが達たっ者しゃ
口が達者 emphasizes eloquence or talkativeness, often neutral or positive, while 口がうまい implies flattery or smoothness with a negative nuance.
お世辞せじが上手うまい
お世辞が上手い specifically means good at giving compliments or flattery, whereas 口がうまい is broader, covering any smooth or persuasive talk.

Compound of 口 (mouth) + が (subject marker) + うまい (skillful, good). Literally 'mouth is skillful', used idiomatically to describe a smooth talker.