They "still can get through" because the DNC isn't a call blocker. You might want to invest in a real call blocker (Google them; many are inexpensive) or at the very least don't answer calls from numbers you don't know.
A woman with a foreign accent that I could barely understand wanted to "verify the info they have on file for me". She then asked if I still use and e-mail address that I haven't used for over 11 years. I told her to take my name off out of their contacts and she hung up on me. Two hours later I got a call from the same number and the exact same thing happened.