You can get rid of both temporary variables that way too. Step 1:

my $re = join '|', keys %vendors;
if($args->{desc} =~ /$re/) { ... } else { ... }
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Step 2: if($args->{desc} =~ /@{[join '|', keys %vendors]}/) { ... } else { ... } Depending on your Perl prowess you may or may not find step 2 readable.

Makeshifts last the longest.