I don't see you second formulation is any more readable.

I'd usually make a local assignment:

for my $field (@required_fields) 
{
    my $form_value = $href->{$field};
    StripLTSpace($form_value);
    defined $form_value or
    return DIRTY $row, "ERROR: required field $k not present";
}
[download]

P.S. In your error clause check for the definedness of the value rather that it's truth unless you really know that all of the potential values must evaluate to true in that context.

--
Clayton