Reet - as Hermann also suggests - as long as the manuscript goes through the usual robust, blinded peer-review process - it is usually fine. Some might suspect if there is a way of identifying the editor as author - such as multiple self-citation.

If it go through a double blind review system then it is on.

Until and unless the journal follows standard review process, it's OK. But, we have seen many editors are biased in publishing their own researches. For academic purposes, there are guidelines that not more than one research is counted in a single issue or subscription as a principal author. But, co-authorship is counted. Reet Poudel

It is not a good practice and a fair review process can't be verified. I have rich experience as reviewer and had seen unethical practices of editors of reputed journals (inviting a reivewer who would favor the manuscript, picking up favorable reviews and croping the negative review reports in the decision letter, deleting the review records from the reviewers profile who submitted a rejection report, waiting until a favorble report is received and so on and so forth). Last year, an editor- in- chief was removed in a reputed journal in Elsevier. He had published more than 200 articles in the same journal. He was found to breach several ethics including cash for publications from authors. If a journal adopts triple blind review system, it may be acceptable. However, practically conversations can happen between editors and reivewers beyond publication realm.

If blind peer-review happens, then it's okay.

Not an issue if blinded peer review is sorted. Nevertheless, the likelihood of publication is high due unavoidable links present. This doesn't mean that a good paper shouldn't be published just because COI may be present.

Can be published but again the links and connections the editor would be having probably increases the chances of the article being published despite the double-blinded peer-review process. Again cannot be generalized but can happen as we all are aware.