Agreed that a transcendental experience ("Mystical" could mean any number of things, fantastic or real, but generally in the mood of the former) can not be verified by the senses - if it could it wouldn't be transcendental - that is why transcendental experiences are validated by two agencies - saintly persons (ie those who have had transcendental experiences) and scripture (information given by god, who is a transcendental entity) -
in the absence of these foundations anyone could claim anything ("I have seen god - prove that I have not" .... or even better "I am seeing god right now - prove that I am not"), which is, ironically, the state of affairs of many religions (no knowledge of scripture and no knowledge of the qualities of a saintly person) that has enabled cheaters to take the position of spiritual leaders. Out of these two the greatest authority is scripture, which is why the first business of a cheater in the guise of a spiritual leader is to change scripture.