To filter the vast majority of the spam, use 4chan filter and put the following string in the comment field:
 
4chan filter: http://userscripts.org/scripts/show/33916
 
Filter string: hh;ttt;eee;ooo;aaa;iii;aa;rh;tf;ccf;tcee;bbd;ccs;fff;ee\se;e\snn;d\sbb;ii;nnr;rrs;ccd;sbb;eef;ssd;elc;