"Predatory" journal, nice expression, I will use that!! I got 3 emails just today from such journals!!
What is really worrying, is that they put up some "pubmed indexed articles" on their website, and fake that they are their own. A quick chech-up on PUBMED revealed that these are articles from other journals!!
Hi I'm new in Researchgate and I know your question has already been answered.
But this article published in March 2017 in Nature is about this topic and is very useful to learn more about and gives some warning signs to detect predatory journals.