I posted about this some time ago in the off topic section. Top is correct other sites just don't seem to have the problem.
Many of the spam post are from Botts and other sites have bott blocking soft wear.
You have to answer questions and do a puzzle on some. Others you have to type in the crazy letter configuration to sign up for the site.
Botts can't as yet do that.
I thank the moderators for cleaning up the mess. Imagine if they didn't what a mess the deer hunting section would be.

Al