faulty_logic("fred");
faulty_logic("wilma");
faulty_logic("barney");

sub faulty_logic {
  my $input = shift;
  if (($input ne 'fred') ||
      ($input ne 'barney')) {
    print "IF condition true: input=$input\n";
  }
}
__END__

Output:
IF condition true: input=fred
IF condition true: input=wilma
IF condition true: input=barney