Expert only, Firefox only, only if you know what you're doing. USE AT YOUR OWN RISK

1. Install Greasemonkey from http://www.greasespot.net/ (you'll have to click the Allowed sites button at the top of the screen and allow the site, then click the link again when you click install) FAQ
2. Click this link to install the script (if the install window doesn't come up, but it takes you to the file itself, go to Tools -> Greasemonkey -> Install script) don't click the "Install" button at the top of the page, it doesn't work
3. A small window should appear with an Install button. Click Install.
4. When you next view blog entries, entries with nasty formatting will just appear normal. Hurrah!