Some journals, even though they aren't actually fake, it is not worth publishing your papers in them. They are just a waste of time and lead to having your papers published in a very low quality journals (i.e., they add nothing to your CV). It is always better to submit your paper to a reputable journal that has an Impact Factor. Journal with impact factors are usually referred to as ISI journals. But be careful that some journals claim that they do have an impact factor but they really do not. You may check whether a journal has an impact factor or not using the following website:
As a follow up, I would consider a journal to be fake if (i) it sends me emails to publish with them, or (ii) posts in social media that they are calling for papers.