There is already a CAPTCHA code when registering, but I think these codes can be bypassed by the more sophisticated bots. I reckon there should be some sort of overly strenuous CAPTCHA-like requirement for all new users, and that they have to enter a code (or a series of codes) for every post they make until they make, say, 5 or 10, after which the codes are no longer required. This would effectively defeat most spam bots.

There are alternatives to CAPTCHA. For instance, you can have it so that there are questions that require human answers instead of just "copy this code". Like "What's 5 + 5 - 2 = ?".

This spam shit is fucking soul destroying...