In my humble opinion, lots of aspects need to be addressed to prevent spam here.

1. First we need to define what is spam like what types of posts will be considered as spam. A proper guideline will help many people to improve themselves.

2. Mega threads should be locked for not giving room to spammers.

3. Most sig. campaigns enforce minimum post limits. This enforces people to write even they do not have enough points to write.

The punishment for spammers should be similar to