Good stuff so far Cory - but not so sure about those 1/2 scale feet !
For a dull, 'dirty' white, you could add just a tiny smidgen of grey to the mix, or alternatively, apply a random wash once the white has fully dried.
Another way would be to start with a base-coat of very light grey, then spray the white in a 'patchy' manner, to allow a weathered, faded look.