The problem with this is that you have to compile a new regular expression for every line of $input. You can do this sort of alternation in a regular expression like

my @patterns = qw/ test good /;
my $alt = join('|', @patterns);
my $re  = qr/(?:$alt)/;

while (<DATA>) {
        if ( /$re/ ) { print "+ $_"; }
        else { print "- $_"; }
}
__END__
THis is a test
this is only a test
now is the time for all
good men to come to the
aid of their country.
[download]

Other than perlop and perlre, a good place to look for regular expressions is the Jeffery Friedl book, Mastering Regular Expressions.