How about a "hide" trust system? You could add people whose judgement you trust to your list, and any posts they've hidden would be hidden for you too.
Really? Is there anyone you trust 100% on matters like this? If someone gets into a petty personal spat then their post(s) should be hidden from you too?
As always, even after thousands of threads and hundreds of thousands of responses about spamming "the board" all over the internet, the answer is: you cannot stop spammers without draconian measures. The best measures that help? Ignore the people who irritate you (you dogooders know who you are), and hit "Report to Moderator" and let them take care of it.
The alternative is ~another~ couple of hundred posts. To save you all some time, I'll list them all here:
1) Ban paid .sigs, and punish everyone.
2) No, don't punish everyone.
3) Hey, I've got a "novel" idea (insert idea that has been suggested 1000s of times before, here)!
4 That won't work because (insert reason that has used to respond to 3, 1000s of times before, here).
5) Suggestion (used 1000s of times before) to modify the swell idea in 3.
5a) Possibly 4, to comment on 5 (1000s blah, blah).
6) Well, I just think some version of 1 or 2.
6a) Comment about how some people ruin it for everyone.
7) Well, I just think some slightly different of 1 or 2.
7a) Find common ground with 6a.
8 ) Repeat 3-7a, endlessly, until 8a or 9.
8a) Discussion gets heated (the dogooders can't fathom that anyone can't see the wisdom of their ideas), then 9a.
9) Someone: GOTO 1.
9a) Helpfully start new thread becuase, this time, THIS TIME, the answer will be found!, then 9.
These aren't spam posts "because, of course."
Now you guys can just post your numbered responses, though with 3 or 4, you have to insert a few words, e.g., "4 some people will cheat."
'Nuff said. 8^]