(mildly) Of very poor quality; unpleasant; distasteful.
That is such a crappy car.
(mildly, especially with "feel") Bad, sick, or depressed.
I'm feeling really crappy - I think I need some fresh air.
(mildly) Covered in crap (faeces/feces).
Put the crappy diapers in the blue pail and the wet ones in the yellow pail.