I tested the following with "dirty" commented and uncommented:

#!/usr/bin/perl -wT
use strict;

my $foo = { clean => 'test.dat',
#       dirty => scalar(<>),
};
open (F,"+>{$foo->{clean}}");
close(F);
[download]

As shown here, it ran with no error. That tells me that $foo->{clean} really is taint clean.

yours,
Michael