I haven't ran into this here. However, I have had a few problems with spammers trying to guest post on some of my blogs. I have even had them get angry at me for not posting their copied work before. I just ignore them and hope they don't waste anymore of my time.
Comments are sometime spammed as well. However, I moderate all of my comments. It takes a little time but it is worth it. Spam gives your work a low quality feel to it. As for hub pages. I have only ran into one comment spam and I just deleted it.
I wish the community was a little more lenient on links in comments. I hate spam but if a comment is good and the link is helpful then I don't consider that spam. Many writers don't take the time to investigate links in comments. I guess it is a time issue. I almost never leave a link in a comment but when I do it is to be helpful not get a backlink and is always on a blog that I regularly comment on. That way the author knows me.
As for bots, I wish they didn't exist. They are very easy to spot if you see one though. It will leave a short and very vague response if it is a commenting bot. It may also try to comment several times. Not a lot of those here though from what I have seen.
I have seen a few spun articles. I spot these pretty easily. They look like a fourth grader wrote them and tried to use big words. If the spammer is using a submission bot like article demon, then it will probably be a brand new user with no picture and a very short bio. They will often be less then a day old with something like 50 hubs. The community here though seems to hate them as much as I do though. These accounts are usually reported and deleted in a few days.
Never heard of any stalkers here. Seen a few trolls though. No big deal though. I just back up and go to the next thing.
Wow. Sorry for the long comment. Just looked up from the keyboard. Didn't mean to write a hub.