In my case, one reason it was easy for me to know that the research studies I participated in were not scams is the fact that I never had to provide any password or access to social media accounts. You might need to be thoughtful about your study and how you explain it in a job posting.
And I can't guarantee that it will be approved.
When I conducted a survey, my first job posting for it was rejected by Upwork. I had to reword the job posting in order for it to be accepted. Even though I was only sending participants a text file with questions (the file was attached to the job posting), and even though it was a real Upwork job posting which paid participants their posted hourly rate.
(In case you're wondering: The survey featured general questions about how Microsoft Access professionals approach database design. Very dry, technical stuff.)
Yes, this particular research stream is proving to be rather complicated, I'll try to use wording that empahsizes we don't plan on downloading anything or posting anything or selling anything in my posting. Thank you for all of the advice.
Please note that you'll need to follow the same procedure as with your other jobs, hire freelancers who agree to your terms and pay for their participation in line with our minimum budget policy.