Just like you were treating plain text as a regexp pattern, you are treating binary data (encoded text) as text. Decode it first. You can use utf8::decode for UTF-8 or the more general Encode::decode.

utf8
Encode

Update: For example,

use Data::Dumper;

$Data::Dumper::Useqq = 1;
$Data::Dumper::Terse = 1;
$Data::Dumper::Indent = 0;

my $s = "\x{E2}\x{99}\x{A0}";        # These are assumed to be
print(Dumper(quotemeta($s)), "\n");  # iso-latin-1 by Perl

utf8::decode($s);                    # ...until you decode them
print(Dumper(quotemeta($s)), "\n");
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"\\\342\\\231\\\240"
"\x{2660}"
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