When resources (image, css, javascript) are embedded using relative paths, the
browser will request them with the language tag. Because these resources would typically be excluded due to filtering, the language tag would not be removed from the URL. The only solution we can find to handle relative paths to resources is to set the QuickUrlExclusionFilter to null.

Because the application might not be installed directly underneath a host name, recommended best practice for ASP.NET is to use "~/images/resource.png" or "images/resource.png" rather than "/images/resource.png".

If I'm understanding this correctly, the QuickUrlExclusionFilter would not be useful in these cases and perhaps a caveat should be added to the manual/wiki to help future adopters.