I'm a moderator (under my real name) on a very large, active gardening forum (phpbb type, like this one).
Spam traffic is very heavy in the early morning hours ("early morning" relative to Eastern ==> Pacific time zones in North America). This is because many "professional" spammers work from China, India, Pakistan, and Eastern European countries, whose time zones are in business hours when North American time zones are in after-dinner and sleeping modes. So, if an American or Canadian comes to the boards before a mod has "killed" the spam (whether reported by others or found independently by that mod), yes, there will be loads of it.
But not for long.