Today, I saw a ton of posts by a ton of different account advertising the NBA. They completly filled the homepage and used up all my flags. What happened and how can this be prevented, since this has been going on for several hours and prevents the use of this site.
I'm not a regular of Server Fault, but I figured I'd just reiterate what Makyen said in the comments in the form of an answer, as I am a participant in Charcoal, the group that runs Smoke Detector.
This particular type of spam influx has been going on for awhile. It typically spams some form of link shortener (such as cutt.ly) or the "crackstreams" link they're using to showcase whatever event they're trying to get views for.
Ordinarily, Smoke Detector would've been configured to cast the necessary spam flags to either delete this kind of spam outright, or at least cast enough that one or two humans could manually cast the 5th and/or 6th spam flag to delete the post. We are currently experiencing an outage of Metasmoke, the site that facilitates autoflagging, because our host is performing maintenance that's going to last somewhere in the ballpark of 24 to 48 hours. As a result, autoflagging is not being performed, which results in certain spam posts not being deleted quite as quickly as they normally would.
So... This is just an unfortunate circumstance of Charcoal performing maintenance, and will be resolved soon. In the meantime, manual flags work just fine, so please keep using them appropriately!
If you're interested, Smoke Detector is still running, just not generating Metasmoke reports. You can monitor Charcoal HQ for incoming spam reports, and flag new posts if you feel it's necessary. At the present time, the spam reports from Server Fault have died down, though.
Yeah, I've been fighting this group of spammers since the Oscars. SmokeDetector is why it hasn't been seen much by people, but has been a real thorn in the side of the moderators. I managed to convince SE Safety to add a few things to our blocked user input list, which has changed some behavior. Yesterday's NBA-fest was the first real test for whether that was enough to dissuade our spammers.
Some, but not enough.
Considering how fast these usually get swatted down (within 5 minutes in most cases) the only thing that explains their persistence is they're paid by the post, not on results. That's a hard incentive to fight.
As for what can be done about them: not much.
This is a problem that has to be addressed at the site-engineering level, if not at the Product Owner level, which means moderators are left with advocating. Which I've been doing. Having been through last night's burst, they're already working out the regexes at play and are busting them. They don't care that their posts (usually) get whacked, have a lifespan of minutes, and don't generate any referral traffic. The only way to fight a group that cares so little about results is to make it harder to post at all.
Stack Exchange has been reluctant to work with me on this.