i-adjective
Describes a place, air, or smell that is filled with smoke, or something that has a smoky quality.
部屋がけむっぽいから、窓を開けよう。
The room is smoky, so let's open the window.
焚き火の後、服がけむっぽくなった。
After the bonfire, my clothes became smoky.
煙い also means 'smoky' but is more direct and less colloquial. けむっぽい adds a nuance of 'smelling/looking like smoke' or 'having a smoky tendency'.
Derived from 煙 (けむり, smoke) + っぽい (-like, -ish), a suffix indicating a tendency or resemblance.