spamfilter.user.js

// ==UserScript==
// @name         Reddit Robin Spam Filter
// @namespace    http://julianhartline.com/
// @version      0.13
// @description  Adds mute functionality and spam filter
// @author       Julian Hartline (julianh2o)
// @match        https://www.reddit.com/robin
// @grant        none
// ==/UserScript==

var storageKey = "RedditRobinMutedUsers";
var savedMutes = localStorage.getItem(storageKey) || '';
$("#robinDesktopNotifier").after($("<input id='mutedUsers' placeholder='Muted usernames, separated by comma'>").val(savedMutes).change(function() {
    localStorage.setItem(storageKey,$(this).val());
}));
$("#robinChatMessageList").on("DOMNodeInserted",function(e) {
    if ($(e.target).is(".robin-message")) {
        var mutedUsers = $("#mutedUsers").val().replace(/ /g,"").split(",");
        var uname = $(e.target).find(".robin--username").text();
        if ($.inArray(uname,mutedUsers) !== -1) {
            console.log("Spam Filtered Message: ",$(e.target).text());
            $(e.target).hide();
        }
    }
});