i-adjective
Western-influenced; Occidental-looking; exotic
Often carries a slightly negative or mocking tone, implying something or someone looks, acts, or smells foreign in a Western way. The literal meaning 'smelling of butter' is the origin but is now mostly figurative.
あの俳優は顔立ちがバタ臭いね。
That actor has Occidental-looking features, doesn't he?
このパン、なんかバタ臭い
This bread tastes kind of buttery (or Western).