also: ていのよい
expression, i-adjective (yoi/ii class)
Describes something that appears good or proper on the surface, often with an implication that it may be deceptive or merely for show. Commonly used with words like 言い訳 (excuse) or 言葉 (words).
彼は体のいい言い訳を並べた。
He lined up a plausible excuse.
体のいい言葉でごまかそうとした。
He tried to deceive me with nice-sounding words.
Similar meaning, but 体裁のいい focuses more on outward appearance or form, while 体のいい often carries a nuance of being glib or superficially plausible.
From 体 (てい, 'appearance') + の (possessive particle) + いい ('good'). The phrase literally means 'good in appearance' and has developed the extended sense of something that sounds or looks good but may lack substance.