This isn't "abuse" by any means. When you have use strict; you have to declare variables. Your example above shows you're not being consistent in your approach. Some variables are declared, for example my $string=shift; while others aren't. Declare %hash, $kv and $vv before you use them. See also:

• strict
• perlintro
• http://learn.perl.org
• http://perldoc.perl.org
• The tutorials section of this site