Not quite sure what you are saying, but neither is behavior different when run as a 'script' versus on the command line via -e, nor is the arithmetic operation 'ignored'.

>cat 0_but.pl
use warnings;
use strict;

print 42 * '0 but true', "\n";
print 42 * '0 but zonk', "\n";


>perl 0_but.pl
0
Argument "0 but zonk" isn't numeric in multiplication (*) at 0_but.pl 
+line 5.
0
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Update: Verfied on ActiveState 5.8.9 and Strawberries 5.10.1, 5.12.3 and 5.14.2.