Every language I'm aware of allows you to write bad code. The differences between many of them simply boil down to how easy it is to screw up. Consistant languages with predictable behaviour will reduce development time, maintenance time, and the number of mistakes made. Obviously if you have expert Perl programmers writing the same code as novice Python programmers the Perl programmers will do a better job.
The real question is what would the results be having a wide range of programmers of all experience levels of each language going head-to-head in a variety of real-world programming tasks. Perhaps it would be an interesting competition?