In my opinion, some cases like JKF (cartel) cannot fool the finest experts, even after extensive reshaping/ lathe work, because their bloody crown/ stem/ tube height is off! It is a fatal flaw that is not acceptable within gen-spec parameters of the gen world.
e.g., JKF (cartel) 5513, 1680, 5512, 1665, st19 daytona cases all have the wrong crown/ stem/ tube height. Furthermore, the JKF (cartel) 1675 cases have the wrong crown size to begin with causing too much crownguard material to be removed: therefore, this fatal flaw is impossible/ too hard to also correct.
But a modified Vietnam case... that is another level and story. I have heard stories before where extensively modified Vietnam cases were able to pass RSC inspection.