Netzero is tracking AND ENFORCING the time you spent online vs the time(s) you have downloaded the add's and such. So although they can't tell if you are running the advertising banner, they can tell when it hasn't updated in x amount of time and compare that vs your online time.
I know of at least 2 accounts that were disabled that way. Neither belonged to me because I don't use, nor have I ever had, a netzero ID.
Just wanted to let you all know that if you do go this route and bypass the banner system, you may want to use an alternative email service (like hotmail or go.com, etc., )so your friends and family can always find you if you have to re-register every now and again.
And if you want to confirm what I said, do a search @ deja.com under the discussions section for netzero and crack. Such as:
LINK