Run this in the devtools console on a SharePoint 2010 page when in edit mode, to strip out some spurious crap from the HTML.

Strip out some spurious HTML.js

/*
    Run this in the devtools console on a SharePoint 2010 page when in edit mode, to strip out some spurious crap from the HTML.
*/
(function($, window, document) {

    var $editables = $("[contenteditable], input[type='hidden'][id*='hiddenStorage'], input[type='hidden'][id*='hiddenDisplay'], input[type='hidden'][id^='ctl00'][id$='content']", ".edit-mode"),
        originalHTML,
        filterHTML,
        $el,
        $filterHTML,
        $removeElements,
        elType;

    $editables.each(function (i, el) {

        $el = $(el);
        elType = $el[0].tagName.toLowerCase();

        originalHTML = '';

        // It'll be an input or a div...
        if (elType === 'div') {
            originalHTML = $el.prop('outerHTML');
        } else {
            originalHTML = "<div>" + $el.val() + "</div>";
        }

        filterHTML = originalHTML;

        // Strip out zero width spaces - see http://stackoverflow.com/a/11305926/13019
        filterHTML = filterHTML.replace(/[\u200B-\u200D\uFEFF]/g, '');

        // Strip out bad HTML classes
        $filterHTML = $(filterHTML);

        // Work around side effect - SharePoint WYSIWYG can break with empty <td> elements
        $filterHTML.find("td:empty").each(function() {
            $(this).text("\u200B");
        });

        // Filter out legacy table styles
        $filterHTML.find("[class*='ms-rteTable']").removeAttr("class");

        filterHTML = $filterHTML.html();

        if (originalHTML === filterHTML) {
            console.info("No changes made.");
        } else {
            console.warn("Made changes!");
            console.log("B: " + originalHTML);
            console.log("A: " + filterHTML);
        }

        // It'll be an input or a div...
        if (elType === 'div') {
            $el.html(filterHTML)
        } else {
            $el.val(filterHTML);
        }

    });

} (window.jQuery, window, document));