This valuable article shares awareness that 1.5% of all accounts are noted as problematic.  While Facebook has improved controls to prevent create fake accounts.  These are out there & often are used for friend requests where the person is actually unknown.  There is danger in getting hacked or for social engineering schemes by those using fake accounts.  Every friend request should be evaluated by visting the FB home page and exploring their friends, photos, and posts.  If you truly don’t know person, then cancel out of request for safety reasons.

http://facecrooks.com/Internet-Safety-Privacy/Investigation-Into-Fake-Facebook-Accounts-Discovers-How-Easy-It-Is-To-Buy-Them.html/

https://finance.yahoo.com/news/bad-guys-build-fake-accounts-facebook-211820178.html

Facebook itself estimates that 1.5% of accounts on its platform are “undesirable,” which adds up to about 30 million profiles. That led some reporters at Yahoo Finance to conduct an investigation into just how easy it is to create or purchase phony profiles—and the results aren’t reassuring.

Columnist Rick Newman first tried to create two fake accounts using different names and with different political leanings. However, Facebook caught on within 48 hours and asked him to upload photos clearly showing his face. Since he’d used someone else’s pictures to create the fakes, he was caught. He also tried to set up imposter accounts through the Tor Browser, but Facebook sniffed out that attempt, too. However, when Newman decided he wanted to purchase accounts instead, he discovered a very different story.

Using several shady sites, he was able to purchase accounts featuring preloaded pictures of beautiful women for $1.50 each. (The most expensive account Newman saw cost $150. It had been on Facebook since 2006.) Most of the accounts were based overseas, but purported to represent Americans living in Milwaukee, Anchorage and more.