Right -- though a hex dump tends to be more useful in cases like this. And of course, if the odd byte happens to be near the end of a large file, this approach can be tedious...

Here's my favorite -- it prints a histogram of byte values in a data stream or file:

#!/usr/bin/perl

use strict;

my @ch;
while (<>) {
    $ch[ord()]++ for ( split( // ));
}
printf "%6d %.2x\n", $ch[$_], $_ for ( grep {$ch[$_]} 0..$#ch );
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And it would be easy to make a couple additions/alterations so that it tabulates utf8 characters instead of bytes.