The question is: how baggy is baggy?  Modeling baggy pants or trousers is always a problem.  There is not enough space around the crotch for detailed modeling or extra material without encountering unsightly bunching of the mesh.  Dynamic clothing might be more forgiving to simulate bagginess, however, contours and bulges will need to be worked into the mesh.  Your best alternative is to apply a morph brush to select areas of your clothing to simulate bagginess.