Testing advertisements across the network

We’ve got over 170 sites – I’ve given up counting by now – and it would of course be absolutely absurd to expect you guys to somehow figure out a whole bunch of ludicrously on-topic ads for each one. But at the same time . . . not all of those sites are exactly prime ad targets, as had been acknowledged a couple years earlier. But from what you’re saying, every site will get these ads eventually, at least in this phase of things.

Source: meta.stackexchange.com