Recessive pied budgies have, in general, mostly clear feathers on all areas except the rump, which remains the original body color. In general there is a patch of normally colored body feathers near the bottom of the belly, with the rest of the body feathers being clear. Where there are marked feathers on the wings, these feathers are half clear near the top. The wings can have anywhere from a lot to very little marked feathers. The feathers on the head are mostly clear except sometimes for patches near the eyes and top of the head.
The recessive pied budgie's eyes are dark plum colored and never lighten with age; they always stay dark. This is how you can be sure a pied is recessive pied, since the dominant pied's eyes lighten normally with maturity. The cere of the male recessive pied also does not change normally. Adult male recessive pieds have purple ceres. Adult female recessive pieds have the normal white/tan/brown ceres.

Basic Genetics:
Normal - dominant
Recessive Pied - recessive
Details on recessive pied genetics...

The recessive pied variety can have anywhere from a mottled splotch pattern of markings to almost no markings on the wings.

The recessive pied almost always has a patch of normally colored body feathers near the bottom of the belly.