I have elected not to join the AFAP for the reasons outlined by several others in this thread (read the title, the part about "what do they do for the Industry?").
Good question thought-crime, and one I'd like an answer to also... (BTW, I am probably being naive, but I don't think it is up to the AFAP or any other union to rectify breaches of IR law committed by aircraft charter companies.)
CR.