I was invited to contribute to a special issue of an MDPI journal. I wanted to warn the guest editor to not get involved so quickly with MDPI. In order to provide some backup to my opinion, I googled MDPI and found this very informative blog entry: https://paolocrosetto.wordpress.com/2021/04/12/is-mdpi-a-predatory-publisher/
Because I am not a WordPress user, I cannot leave a comment. By the way, the comments are as interesting as the original post, which the author is apparently continuing to update. Here I am sharing my experience with MDPI.
My first encounter with MDPI was about a year ago through a special issue, guest-edited by a researcher whose work I had been following. I accepted the invitation and submitted a manuscript. The turn-around time of the initial review was within two weeks, which impressed me. Then in the revision process, which was required to be done in a week, my co-author and I were asked to move the manuscript into the publishing format as if we were the copy writer tasked to move the content into their journal template. I did not question it but wondered how inconvenient for reviewers to read the manuscript in tiny fonts and single space. Soon the manuscript was published after again a quick review period and paying the publication fee. Note that it was PUBLISHED, not just accepted. In other words, we provided free labor to not only write an article but also proof-read our own writing and have it ready for publication. I started wondering what the staff in MDPI did in all these and why they dared to charge thousands of dollars?
Afterwards, I started receiving review invitations almost every other week. I could not accept them for most of time I had little expertise in the subject matter or I was not available to review something immediately within 7 to 10 days.
Recently I accepted the invitation to review a manuscript within my field. It was a bad manuscript, and I recommended a rejection. The editor deleted my recommendation (rejection), modified my words (so that there was no trace that I had rejected it), and asked the authors for a revision within 7 or 10 days. I then received a revision. Well, of course the quality of the manuscript did not improve much because who can turn a rejected manuscript into an acceptable one in such a short timeframe? I rejected it again and left a strongly worded note to the editor, who I doubt had any expertise in the subject matter in a broad sense. This was when I start questioning the credential of the MDPI editors. Yeah, the editor did reject the manuscript this time.
I have received multiple invitations from MDPI to be a guest editor on certain special issues this year. I ignored them but then received follow-ups. I replied that I had a day job and a life (not exactly worded like this) and could not do all they were asking me to do and please stop emailing me. They have not stopped. I never accused them of being predatory when replying to their requests. But I feel differently after reading that blog entry. It is a shame that MDPI does not seem to respect time and expertise we scientists/science authors offer for free, and cares little about the quality of their publications.