An approach that has served me well (perfectly so far) is to decode everything to utf8 first and then re-encode it to entities. It works because decoding a plain & is a no-op. So you're essentially normalizing the text and then encoding it. You will lose your original entities but the new ones will probably be better as they will be uniform. I recommend numeric entities; the example shows named ones. 

use strict;
use warnings;

use HTML::Entities;
use Encode;

for my $line ( <DATA> )
{
    # This is a no-op on plain &s
    my $utf8 = HTML::Entities::decode($line);
    print Encode::encode_utf8($utf8);
    my $proper = HTML::Entities::encode($utf8); # OR encode_numeric()
    print $proper;
}

__DATA__
Purus Accumsan Felis &#8240; Maecenas Nibh &theta; Eget Phasellus & Mi
+ Amet.  Odio Amet && Purus.  Mi Ullamcorper Lorem Eget Nibh.

http://www.example.com/?name=John&residence=Vatican+City&job=Pope

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In reply to Re: Matching ampersands that are NOT part of an HTML entity? by Your Mother
in thread Matching ampersands that are NOT part of an HTML entity? by Anonymous Monk

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