Predatory publishers operate in many ways, using academics' need to have research outputs such as publishing or presenting at conferences to disseminate their research, to extort money. Academics can be spammed and invited to publish with the promise of quick and easy publication. Fake journals with titles similar to legitimate ones are one of the methods used in the scams. Authors are invited to publish and asked for a fee upfront, their paper is either published without any editorial work in a journal with little or no credibility within scholarly circles or not published at all. In some cases people have been invited to present at fake conferences. These scams are sophisticated and may link to websites that initially look legitimate. The scams evolve rapidly so there is a need to be vigilant, question and investigate to avoid being a victim.
A useful resource is the OASPA (Online Open Access Scholarly Publishers Assoc.) website which has lists of legitimate Open Access journals and links to a guide, Think, Check Submit that provides advice to researchers so they can make an informed choice about where and how to publish.
Previously there has been some reliance on lists of journal titles and publishers who were seen as not following ethical processes or not adhering to trustworthy models, Beall's List was the best known list. This list is no longer being actively curated and it has been removed from the guide.
The research community needs to use scholarly social networks to identify and share information on publishers that deceive, lack transparency or otherwise fail to follow industry standards.