i-adjective
countrified; unsophisticated; uncool
Colloquial and derogatory term for someone or something that seems rustic, unfashionable, or lacking urban polish. Often used to mock a person's style, taste, or behavior.
あの服、ちょっと芋臭くない？
Those clothes are a bit countrified, don't you think?
彼の話し方は芋臭いけど、それが逆にいい味出してる。
His way of speaking is unsophisticated, but that actually gives him a nice character.
More directly means 'smelling of the countryside' and can be used literally or figuratively, while 芋臭い is more slangy and derogatory, focusing on lack of urban sophistication.
A very common slang term for 'uncool' or 'lame', but 芋臭い specifically implies a rustic, countrified uncoolness rather than general tackiness.
From 芋 (imo, 'potato') + 臭い (kusai, 'smelling of'), literally 'smelling of potatoes'. The potato is associated with rural, earthy simplicity, giving rise to the figurative meaning of 'countrified' or 'unsophisticated'.