One reason my stuff usually fails is due to empty elements. For example: <div class="clear"></div> in order to clear a float or something. There are better

One reason my stuff usually fails is due to empty elements. For example: <div class="clear"></div> in order to clear a float or something. There are better ways to do this but nothing is more convenient than riddling your markup with non-semantic garbage. If your website renders as expected in all major browsers, I say don't worry about it. Also, if it renders like crap in IEX, don't worry about it. IE users are used to a horrible experience online. They see broken websites all the time and just assume their computer has a virus. And it probably does. It's just not causing their poor web experience.