If you see a spam post or a get a spam PM, the best way to raise the red flag is to report it. You can also notify my other channels in addition to reporting, but the reporting will always make it easier to find and delete the spam. Please don't reply to the spam posts, as it risks your being caught up in the net and I don't want to accidentally delete a valid user!
The main issues that the spammers have started making what look like real posts at first, so unlike 99% they don't get caught early. The site actually gets fairly regular waves of spam, and thankfully very little gets through.