Physics Stack Exchange routinely closes questions that presume "non-mainstream science". I do not know their policy with regard to whether answers based on "non-mainstream science" should be flagged for moderator attention, nor have I had occasion to flag such an answer on that stack exchange.
However, recently an answer appeared to a question on EESE which appears to me to be based upon and promoting "non-mainstream science". If I felt the answer to the question were merely wrong, I would simply downvote. I think this site is open to people who make errors, and the remedy is to simply vote down the bad answers and vote up the good. I'm not always happy with some of the answers that are accepted or with which answers receive up votes, but voting is the means we use to resolve these issues. We don't struggle endlessly to ensure that our opinions of the best answer prevail.
This case, I think is a bit different from a simple case of error. I think the author is quite aware that his answer is based upon "non-mainstream science"
The above electromagnetic theory is not the classical electromagnetic field theory. Classical electromagnetic field theory do not accept the advanced wave, because it Violation of causality. But there are lot of scientists believe the advanced waves are real objective existence. The above electromagnetic field theory is the mutual energy theory developed by shuang-ren Zhao
"Mutual energy theory" and the writings of shuang-ren Zhao have found a home with the publisher Scientific Research Publishing (SCIRP). Wikipedia describes SCIRP as a predatory publisher of questionable quality.
The company has been included in a list of questionable open access publishers,... Beall states that "This publisher exists for two reasons. First, it exists to exploit the author-pays Open Access model to generate revenue, and second, it serves as an easy place for foreign (chiefly Chinese) authors to publish overseas and increase their academic status."
I have a sense that some subtle promotion is going on, i.e. the promotion of "mutual energy theory" or its developer. But is the promotion so odious that it rises to the level of spam? Is up/down voting where this sort of answer should be left? Or, should other action be taken with respect to answers like this? Should contributors flag answers like this? If so, on what grounds?
The specific answer that prompts these questions is here, but I am more interested in the general principles of how to deal with this sort of thing, than I am in the outcome of this particular case.