All rules are applied by IE5/Win. IE8 when emualting IE5 quirks mode will not honor escapes in the property background. This is correct behavior since this deals with box model issues.
Control
bac\kground:#6ea; - filter IE5/Win
back\ground:#6ea; - filter IE5/Win
backg\round:#6ea; - filter IE5/Win
backgr\ound:#6ea; - filter IE5/Win
backgro\und:#6ea; - filter IE5/Win
backgrou\nd:#6ea; - filter IE5/Win