I have no idea which adnetwork are we talking, can you provide the link?
One problem that might exist with such decentralization though is that the adult sites can infiltrate the sites not suited for displaying skins. This is why there are adnetworks which only focuses on single niche because big adnetworks like googleAds are restricting all these from gambling to adult sites.
Publishers can pick which ads can be displayed to their pages?
VAD is simply one function in the anonymous network of VDS project. Here's its official deep web site: VDSVVVXXMXPSSSZD.ONION
Don't forget to use Tor for the deep web.
To answer your question, as long as you published a VAD, it is written on the blockchain, so everyone with access to VDS wallet can receive it. Your content is the ad inserted into every user wallet.