Your claim that it is impossible for APs to catch cheating involving marked cards is both false and dangerous. You were refuted on this point, and retreated to claiming that you were right because some of it is difficult or impossible to detect. That doesn't in any way make your earlier claim correct or not dangerous. Some of it is detectable, and APs should know how to detect it.


Furthermore, even if you can't catch the marks, you can still catch the second dealing.