I am sure theymos is well aware of the problem, so are the mods and staff of the forum, but how do they prevent this?

In fact, I think theymos is doing an impressive job in tacking these issues wherever possible. The forum has measures like 'units of evil', a good trust feedback system; along with a strong moderation system which gets significantly better in the new forum.


The community + moderators find and remove spam and off-topic content, and ban members who are found abusing or breaking rules and so establishes a check on these farmers' activities, but this is not exactly preventive beyond an extent.

To disincentivize farming I see two choices:
Restrict account trade to the maximum extent.
Restrict signatures or signature campaigns.

A lot disagree with both (reasons being potential ineffectiveness, personal interests and potential negative impacts), so it is unlikely there will be any significant changes to come.