Short of blocking them with a host file addition after finding the adhost, one can block notifications for individual apps via the app info (hold press on notification and select app info).

Must be on Android 4.1+ I believe though. I dont think ICS had it. There's also a bug in blocking notifications for 4.1 that inadvertently blocked Toast messages within apps as well, but it was fixed on 4.2. Just something to be aware of if you go blocking them and a developer was not aware enough to avoid putting important info in Toasts.

Guess I've been pretty fortunate because I haven't seen this.