Is there any validity in so-called “reverse speech analysis?”

This has some ability to reveal hidden meanings and subconscious truths. There are many abuses and with any such scheme that depends on the subjective interpretation of a listener, there can be more than meets the ear, or less. And so it is valid in some settings but not valid in others, depending on the nature of the subject material and the speaker. So there must be material that is objectionable to the speaker in order for a subliminal message to be interwoven in this way. So someone who believes totally in what they are saying will not generate any inner conflicting emotion or awareness on a level needed to cause formation of a subliminal speech pattern that can be revealed by a reverse analysis. So there are many caveats and many pitfalls, and as a consequence, the validity must be considered on a case-by-case basis.