without the fragile use of utf8 function calls
Although you're certainly right that several of the functions from utf8:: should be used with extreme caution (or not at all), AFAIK using is_utf8 to check on the flag for debugging (only!) should be fine. I was just trying to provide a slightly "nicer" debugging output because slugger415 said "I'm not a developer, just a Perl hack, don't grok hexdump or Devel::Peek etc.".
slugger415: I just wanted to add that I wasn't necessarily suggesting you should try to understand the output, it's also very useful information for us to help you debug.