while the list is not provided as an evidence based indicator of relative credibility, Beall's site and blog do give quite a bit of 'food for thought'. There are certainly a number of dodgy publications, and like many I have been bombarded by invitations to publish, act as a guest editor etc. If you dont work for an organisation willing to pay the cost for open access publishing, it is an expensive option for individuals. There needs to be a clearer means of determining relevance and credibility of material at times.