bpl is getting hit by not running its own forum software. These are all fully automated attacks, it's useful to stop thinking of spammers as people, the stuff is done by tools running automatically through lists of targets, and other lists of targetted links and search phrases, with some customization possible. The spamming software tools used just saw a huge improvement in quality, far more robust than they used to be, Russians tend to be very good at this game.
By allowing posts to remain, you are providing a high quality target in terms of seo (search engine optimization, aka, spammers) with high value pages, about the best they could hope for. You need to remove all spam postings as soon as you humanly can, deputize a few people if you need to, otherwise you going to have even worse problems. Remember, a spam posting is NEVER made by a real person, so the procedure should always be this: detect new spammer username, get list of all posts done by user, freeze user asap, but do not delete yet, then delete all postings by that user, then delete the user, tedious, but if you do it fast enough, not too bad usually. Also, they don't usually post too much until they think they can get away with it.
I've pm'ed roger about some technical issues that don't benefit from public discussion, but if you don't get a handle on this quickly you may have bigger problems.
Flagging postings etc does little good, though it can help find postings that the mods may have missed. Ignoring or leaving up spam postings, as bpl has been doing, is NOT one your options, unless you want to terminate this site and move on with life.