As a first, I recently received an invitation to peer review for a predatory (or at least shady) conference - in contrast to the tons of unsolicited invitations to publish papers with their journals or speak at one of their conferences (which always involve a publication fee payable by yourself). The email had all the hallmarks of a typical predatory request (including being adressed as "Dear Scholar" instead of my name), a quick look at their website confirmed the suspicion.
Normally, I always directly dismiss these kind of emails, but this one is different, as it doesn't ask for money and instead asks for peer review - a process that normally should lead to higher quality publications - a sign that the "shady" conference is trying to improve and become a more reputable outfit in the future?
Therefor my question: Is reviewing for disreputable journals/conferences a waste of time and not worth it, or is it helping towards the improvement of publications?
