If I understand correctly, The rexcube is a "deeper-than-deep-cut" puzzle.
Master skewb has "deeper-than-deep-cuts" as well as shallow cuts.
Despite a lack of consensus on what "deep cut" really is from a puzzle-theoretic point of view, this is not correct. Everyone agrees that a Rex Cube is not deep cut. The Master Skewb is also not deep cut. There is no argument on these points.
Regarding Depp Cut puzzles, the community consensus seems to be that those are the puzzles that look like this:
depp_cut.png [ 345.39 KiB | Viewed 301 times ]