decode already handles bad UTF-8. 

$ perl -MEncode -Mcharnames=:full -wE'
   $bad = "\xE9abc";
   say sprintf "U+%04X %s", ord, charnames::viacode(ord)
      for split //, decode("UTF-8", $bad);
'
U+FFFD REPLACEMENT CHARACTER
U+0061 LATIN SMALL LETTER A
U+0062 LATIN SMALL LETTER B
U+0063 LATIN SMALL LETTER C

[download]

It doesn't remove bad characters, but replaces them with U+FFFD. You could play with decode's third arg, or you could simply strip out the replacement character aftewards. 

s/\x{FFFD}//g;

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In reply to Re: Filtering out bad UTF8 chars by ikegami
in thread Filtering out bad UTF8 chars by FreakyGreenLeaky

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