How about creating a client side fully customizable word blacklist that the players themselves can edit. Where a player can enter a word or phrase that if found in a string of text will filter it. To help prevent uneeded filtering the player can also select which channels the blacklist will be applied to (Say/Tell/Etc). Letting the players themselves handle it will make it much harder for the spammers to compensate as opposed to them just having to get around SE's list.

It also adds a fair bit of randomness to the equation as there are many parts of a spam text that can be used to block the text and while changing one thing in the spam may get through to certain players (until they add the changes text to the blacklist) it will still be blocked by others who weren't using that text string in their list.

This idea would theoretically make it much harder for them to get their messages out as they are being filtered out of chat by the players themselves rather than SE.