“Presumed predatory journals are abundant in oral health”, Journal of Evidence Based Dental Practice, March 2021.
From the 580 potentially eligible journals, 431 dental journals were included [and] 226 PP (52%) [i.e. were PP, “presumed predatory”]
Mention or reporting to be indexed in the Directory of Open Access Journals (DOAJ) database and a journal website with distorted or blurry images were the most influential variables for accurate classification into a predatory category or not.
Slightly badly phrased, on that last quote. The authors seem to want to state DOAJ listing = OK (if the link works and the journal’s DOAJ page can be found), while the inability to resize a logo picture correctly = dodgy. But their abstract’s sentence implies the reverse.
But yes, I’d agree that there does seem to be a curious and innate inability among makers of predatory journals to resize pictures correctly, though my eyes are perhaps better at spotting the subtleties of such things than many. Artists and designers tend to forget how dull most eyes are, in terms of not being able to see such details at a glance. Actually, I guess you might even bypass that problem — by training an AI to search for predatory journals through looking for logos and other images with incorrect proportions (squashed, stretched), or prestigious logos that are blurry when they should be crisp, or which have subtly colour-shifted. Bad use of naff fonts is also a tell-tale, I’d suggest, though that would be more difficult to train an AI for. But even just trawling for the DOAJ logo and a couple of other common logos would be an interesting experiment.