Consider an undergrad student (who wishes to dive into STEM research) in an obscure university in an obscure town who has a few ideas which he converts into a well documented article. All of this by learning completely on his own. He has no faculty within his institute (or locality) to turn to (they aren't as active in research) for help.
Where should such students/learners try to get comments/criticism on their work?
- Sending it out to publishing is not a good idea because it will get rejected with cliched answers and will rarely help the candidate improve his work.
- Stackexchange/Quora/Reddit etc. are great for small answers but it is too much to ask to read and rate someone's work
- One can send out mails but Professors/Grad Students/Researchers in the field might not have the time to reply to such mails. Further, if the work is fundamentally flawed, the student might never get replies.
- Any other repository site (ArXiv?) might cause the paper to be drowned by more successful ones and the student might never get comments.
What can he do?
It may be that even if the faculty at the institution are not themselves active in research, they are likely to know people they are (after all, they got their own degrees somewhere). The best route, if at all possible, would be for one of the the local faculty to put the student in touch with someone who is active in research. The personal introduction makes it much likely that the work will get actual feedback. (I'm assuming here that the student has actually talked to the local people and determined that they're not interested; just because a faculty members isn't currently active in research doesn't automatically mean they don't care and won't be able to help an interested student.)
If that's not an option, the student might be able to meet researchers through some sort of event, either one aimed directly at undergraduates (for instance, in the US, there are many summer programs for undergraduates), or even just by attending a conference and trying to meet people. This may not be an option (summer programs require being accepted, for instance, and attending a conference on one's own can be expensive).
If that's off the table as well, it may be time to personally e-mail researchers in the area. It's true that there's some risk the work will be ignored, but there are steps that can be taken to minimize this: choose a person to contact carefully, making sure it's someone actually interested in the exact topic of your research (on the one hand, you want it to be someone you cite, or at least someone who's worked directly in the area, but on the other hand, you don't want to e-mail the biggest name who has anything to do with the subject); and write a personal e-mail which makes your situation clear without being too verbose, and which explains why you're e-mailing this particular person.