Now, this problem has been around for a while now, and still I from time to time see someone on my flist wondering about this.
Who are these strange people randomly adding me?!
Today alone, I have already got 9 friend requests. And it's only 2pm.
Now, it is very easy to report a bot. You can get right to the link when hovering over the icon before the username (or, use this link, provided by kit84).
Here, I thought to compile a list of ways to recognize a bot (ones I've discovered; I could be wrong or miss something).
So, the most usual ways of spotting a bot:
Those were just off the top of my head. Feel free to add stuff in the comments, and I'll add them to the list ^^