auto-block hosts who return bad/virus results
 

It is clear that some people are running gnutella clients that are infected viruses. These machines will *always* return a positive search result, using your exact choice of search words, but with a filesize of 28kb, 301kb, etc.

Why can't Limewire recognize this condition, maybe do a secret test search for some garbage keyword, and then automatically IP-block all hosts that respond in the positive?

yes, people are apparently attempting to use gnutella searches for advertising. an easy way to add thier IP to a list from which limewire would just refuse to do any business with would cause them to slowly fade out of prevailance.

AquaLime
 

The AquaLime coder implemented something like this in his distro of the LimeWire client ... check it out ... you can d/l it from sourceforge or unite the cows. just do a search for it on google.