The term predatory publishers was coined by Jeffrey Beall, Librarian at the University of Colorado at Denver. He had a list of unserious publishers/journals, commonly known as Beall's list. It has now been removed from the web, but others have taken on the task of trying to keep it alive. Stop Predatory Journals is such a site. However, some have the view that the list was too broad in its assessment.
The following are some characteristics of a questionable journal
They often claim to offer a fast peer review but, in fact no review is made. Articles published in these journals are usually not taken into account in bibliometric or other assessments of the researcher's CV. It is also rare that they are cited in serious journals.
These publishers often have sites that look serious. The journals often claim they have editorial boards, impact factors and that they are indexed in well known databases.
Editorial boards may consist of persons who cannot be considered to be qualified or persons who have not agreed to participate. Impact factors may come from various sites on the web that provide fake impact factors.
Predatory publishers often use aggressive email marketing where researchers receive offers to publish in their journals. In many cases, they also have a conference activity linked to the publisher. There are also examples of serious journals kidnapped by dubious operators who set up a website similar to that of the true journal. In some cases serious publications have been sold to questionable publishers.
A good article on the subject is Eriksson, S & Helgesson, G. The false academy: predatory publishing in science and bioethics. Medicine, Health Care & Philosophy 20 (2017) 163-170.
How do I know if a journal is dubious?
On our page Publish stategically, we provide suggestions on how to make a simple check if the journal you are interested in is in fact dubious but best is to contact us at email@example.com. We will also be pleased to come and talk to departments and research groups on these matters.