How to know if a journal is to be trusted?

The question of whether this particular journal is to be trusted bugs me everytime I’m ready to submit a completed article.

It appears that many researchers have the same problem.

Here there are two excellent lists of journals not to be trusted and publishers with questionable practices (lists have respectable 507 and 693 entries). Ideally, one should think twice before submitting to any of the journals/publishers in these lists. Also there is a list for misleading journal metrics.

Jeffrey Beall created a neat list of criteria of a problematic journal. If a journal follows at least some of the mentioned practices, you’d better consider submitting your manuscript elsewhere.

Another interesting website calculates impact factor for journals you enter, it seems legit.