I recently sent a FAIL result to the cpan-testers for a module. It turns out that the module was fine, but the data source it was written to talk to was broken.
The breakage is that instead of sending this:
<?xml version="1.0" encoding="UTF-8"?>...and so on
they sent this:
<?xml version="1.0" encoding="UTF-8"?>... and so on
There's already a module on the CPAN for dealing with doubly-encoded UTF-8. Perhaps someone needs to write XML::DoubleEncodedEntities as well :-)