Yes and no.
Typically, about 25 spammers make it through the CAPTCHA hurdle each day before I dutifully delete them. Maybe about one in 25 actually posts to the forums, as opposed to just sitting there in the list of members. (I suspect this latter is a strategy to improve search engine ranking.)
For the last few days, we’ve been getting about 350 spammers making it through CAPTCHA. (There is probably one actual spammer who has placed this site on his list for bots to attack. After banning yahoo.co.uk, this number has been reduced to about 75—still about three times the normal rate. Hence we’re seeing about 3-4 spam posts a day as opposed to the usual 1 per day.
This has happened before. Typically, the surge stops after about a week, and the rate returns to normal. The only thing different this time was the use of yahoo.co.uk instead of gmail. Since we have so few legitimate users from that domain, I could ban it. Gmail remains the preferred domain for spammers, but because of the number of legitimate users who use Google, I can’t ban it without strangling all traffic to the site. (Google remains startingly uninterested in the fact that spammers are abusing their service in this way. They’ve been of zero help, not even sending automated “thank you for your concern” emails in response to my attempts to alert them.)