elsif (
  $input ne 'good' and
  $input ne 'bad' and
  $input ne 'iffy'
){
next;
}

##</code><code>##

elsif (
 $input !~ /good|bad|iffy/
){
next;
}

##</code><code>##

my %lookup = (
  good => undef,
  bad  => undef,
  iffy => undef,
);
# and then within your loop
next unless exists $lookup{$input};