Some of us pay Level3 four or five figures a month. I checked and receive NXDOMAINs (like I should) but I would immediately open a ticket if they were fucking with my DNS.

That said, we run our own recursive servers and don't rely on Level3's.

You say that, but if they weren't meant for public use, they wouldn't be accessible to the public. Time Warner's DNS, for example, are not available from outside their network.

And if your car is unlocked it's meant for joyriding?

If my car became very well known for being unlocked and immensely popular with people taking joyrides, then yes, my continued unlocking of the door would constitute tacit permission.