I have a feeling this is not the review Sony was hoping for, but definitely what we'd want to know.
We're in definite agreement in our sentiments about the mediocrity of Rhino Custom.
I miss the golden days of Rhino Handmade, when they put out daring (for a major label imprint) and relevant releases with a high standard of musical quality. Those two singles comps (as you reference) were superb and highly enjoyable. They adhered to the basic rules of compiling.
A compilation should always have a unifying theme (all the chosen songs being on the same label is a start, but not the main unifier). There should be a musically logical flow from one song to the next; each following song should make sense in relation to the preceding one, whether a similar feel or a deliberate jarring change to keep the listener on his toes (figuratively speaking).
From your review this sounds sorely lacking in the set, whcih would fit with the crank out product attitude sorely lacking in the Handmade series, but seeming to be the raison d'etre for the Custom imprint.