Recently, I've had lots of bots add me (10-20), and most seem to be run by the same person/organization.
They usually say things like
Then comes the obligatory (fake) Steam community page, usually a minor misspelling like "commnunity" or "commumety".Hello mate. My friend in fb ask me add you. He want to talking with you, but he can't add you, have an error...
Another variant is tells you to click some link or copy it to your browser, but those are pretty easy to spot - however, the link (and domain) changes nearly every time.
This shouldn't be a problem for most people, but I've decided to accept every friend request I get from the bots and report them with every message in hopes of preventing other people from getting hijacked. I'm not sure if someone specific is leading the bots to me on my friends list, or if there's just a resurgence in activity. Also, most of the bots I've seen seem to be 5 years old (the account was created in 2009) for whatever reason.