Here is a link to a research paper on the subject, based on an ethically questionable experiment: https://www.reddit.com/r/netsec/comments/38wl43/we_used_sock_

Here is a link to a research paper on the subject, based on an ethically questionable experiment: https://www.reddit.com/r/netsec/comments/38wl43/we_used_sock_puppets_in_rnetsec_last_year_and_are/ https://www.reddit.com/r/netsec/comments/38wl43/we_used_sock... tldr: it's extremely difficult to detect and mitigate, relatively easy to do (assuming you have some technical skills), and quite effective