nwr suggested one way (thanks nwr!).
These "journals" are "published" on the net. This makes it quite easy to look for the sponsoring professional society or university or the editorial board. If none of these is mentioned anywhere, the red lights should start flashing. If one or more of these appear, go and do some research on it.
It takes some time, but it's worth it, I guess.
Edited by Pressie, : No reason given.