The same goes for the United States Dollar and the Chinese Yuan...they are used for criminal activity. It doesn't define Bitcoin because it's found on the black market, 80-90% of people who use bitcoin use it for legitimate purposes.
The most appropriate post here in the thread. I like the subject - bitcoin is NOW used in crimes. So actually it's used in crimes just NOW. And gold coins, dollar papers, euros, roubles, etc were used since the beginning of the time - name changed and value. And sure the way how you identify and keep it.