Protect Against Form Bots / Spam Bots

[eluser]LuckyFella73[/eluser]
A simular option is to set up a hidden field containing
a default value. Change that value with javascript (after
document is loaded) to an other value and then check
in your controller if the value is equal to the value js should set.

I read that spam bots usually don't support javascript so
the value would be the default one (or an other, in case the bot
changes the value) when submitting.