Someone in this industry who does no personal hacking, c.f. has no code of his/her own to show could be a good hacker but... the odds against are high. I think 80% of my skillset came from working on my own projects. At work there just isn't always time or chances to learn and explore and it's rare to get into a good mentorship where you're learing from a significantly superior hacker. (80% of my good practices came from hanging around the monastery, incidentally.)

Now for the anecdote. Couple years ago I had a contract that was making me insane when a job that was exactly what I wanted appeared on the boards. I wrote and CPAN'd a module related to the position as my cover letter. I got the job and with the highest salary I'd ever had by a lot.