i switched from reCAPTCHA to regular questions,
since then not a single spam bot.
with reCAPTCHA + email verification - i had new Viagra and drug commercials on a daily basis
and a hell alot of porn spam.
was thinking makeing a porn and drugs site, content is bot created

(just kidding)
well now im running Question verification and email verification,
havent had a single bot register in more than 2 months, where before it was daily.