I'm not sure what your $res->content is, but if I put your XML into a file named file.xml, I get this expected output:

use warnings;
use strict;
use XML::Smart;

my $xml_parser = XML::Smart->new('file.xml') ;
print $xml_parser->{feed}->{'openSearch:totalResults'},"\n";
for my $entry (@{$xml_parser->{feed}->{entry}}) {
    printf('%s - %s%s', $entry->{'title'}, $entry->{'gd:etag'}, "\n");
}

__END__

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Fitzwilliam Darcy - "Qn04eTVSLyp7ImA9WxRbGEUORAQ."
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