unvertisement 

An advertisement so incredibly annoying that it actually puts you off whatever it advertised.

I hate those unvertisements where they're having a clearance for furniture or carpets and someone is constantly shouting. They don't make me want to buy stuff, they make me want to find the manager of that place and shove a screwdriver down his ear canal.

unvertisement by Korgmeister April 22, 2006

Unadvertisement

An advertisement which is shown so often that it reduces the chance of you buying the product, through sheer disgust and rage.

With the number of unadvertisements I've seen to buy Rihanna's new single, there's no way 'm getting it now.

Unadvertisement by TheBald March 12, 2010