Assuming that you don't want to strip special characters out of quoted phrases; this is shorter, but uglier. It should handle backslashed quotes as well:

#!/usr/local/bin/perl -w

use strict;
use diagnostics;

my $str="foo bar -\"weenie roast\" +\"'foo' bar\" \\' -baz +boo +bee /
+ +ben fat   faz -slim 'ooga booga' 'fee fie \\' foe fum' \\'do ray\\'
+";

my (@KeysNeed,@KeysAvoid,@Keys);

1 while $str =~ /\+(\w+|((?<!\\)['"])(.*?)(?<!\\)(??{$2}))(?{push @Key
+sNeed,$3||$1})|-(\w+|((?<!\\)['"])(.*?)(?<!\\)(??{$5}))(?{push @KeysA
+void,$6||$4})|(\w+|((?<!\\)['"])(.*?)(?<!\\)(??{$8}))(?{push @Keys,$9
+||$7})/g;

use Data::Dumper;
print Dumper(\@KeysNeed,\@KeysAvoid,\@Keys);
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