Do you have difficultly reading craigslist ads because everything is in all caps and has ridiculous punctuation designed to grab your attention. Try installing this greasemonkey script using firefox’s greasemonkey extension. The source is reasonably documented, so if you come across a special character that I didn’t put in there you should be able to remove it. Unfortunately this doesn’t help the ads make any more sense if they didn’t make sense in the first place.
After (the text only appears larger because wordpress downsizes the image less because it is less wide from having fewer characters, and fewer capital characters (which are wider in non-fixed width fonts)):