Do you mean "big projects" or "production code". To me "production code" makes my workplace productive - I have a pile of Perl script sitting there doing that job: Perl is hugely productive.
On the other hand I would be unlikly to use Perl for a really large application - Perl provides far too much rope and no tensioners to manage the slack. The bottom line is that there is no one language that is best for everything. Perl is damn fine for a lot of stuff and can be written to be maintanable for sure. I've even had to maintain some of my own code so I know it's possible. :)
DWIM is Perl's answer to Gödel