difficult to distinguish can nice difficult to smell in something else
smell is important_sense. strong_odor is tangible_thing. unpleasant_taste is not tangible_thing. smell is not important_sense. strong_odor is not tangible_thing. pleasant_odor is tangible_thing. pleasant_odor is not tangible_thing. unpleasant_taste is tangible_thing. smell is not sensation. clean is not tangible_thing.