Ok, I can chip in in this comment (finally!)

First of all: I'm a moderator in the subreddit that caused the biggest downfall of a website outside reddit for vote rigging (quickmeme). I wasn't a mod back then, but I did was one when the second one fell (memegenerator).

I'm going to talk about spam and about memegenerator & its vote rigging.

Spam:

In my subreddit we used to have LOTS of spam. Our moderating job was probably 75%~ deleting them. Blatant spam. The sub is based on sharing memes (yep, it's AdviceAnimals if you hadn't noticed yet), so when we found a post that didn't linked to a meme, the post was inmediatly taken down and flagged as spam (if we caught it, sometimes, the spam gets past of guards).

An example of that "spam that gets past our guards" happened the same week I got promoted: a random user posted something from a random meme maker (I don't remember its name right now) and used bot accounts to upvote it and get it to the front, where everyone who opened reddit at that time would see it. They'd open it (the link wasn't RES-compatible, so they couldn't open it without clicking) check the meme (a rather lame one, btw) and close it. No harm done, right? They didn't knew it got upvoted by bot accounts, so they made no harm? Wrong. Turns out that account was a pretty new one, with just 2 or 3 submissions from imgur (so it would look like a normal account for the mods) and then submitted the submission from that unknown page.

We get 600k~ visits on a daily basis, let's say that 500k~ clicked it. That website had 4 or 5 ads IIRC, so BAM! Some random guy on the internet made 10k~ $ by gaming reddit once.

And as I see it, sharing something "to the top" in hubski could be as easy as vote-rigging something in reddit (as far as I know, maybe you have a way to prevent that that I don't know).

Memegenerator & vote-rigging.

| And even those can lead to a massive conspiracy like memegenerator. |

Some of my mates in the mod team actually thought that the vote-rigging made by memegenerator was fake (fake in the sense that they didn't promoted it, but instead someone else made it to kick them out of reddit), me included. The vote-rigging was ridiculously obvious (23-4 on a submission made 7 or 8 minutes ago, 3-1/4-0 on everything else). So far we have no proof about that (the only ones who could give us are the admins, and they didn't contacted us, so who knows).

Probably this comment looks a tad crazy, but I just want to high-light something: do you have any way to prevent...mmm... "share-rigging"? [I apologize before-hand for any grammar mistake I could have made, I'm not a native english]