In terms of fault, we're doing what we can to filter it out when it hits us, but nothing particularly sophisticated yet. On other exchanges, our filters filter out some significant percentage of traffic, but the same filters applied on Adx don't get triggered often. The click and conversion behavior of ads shown number seem to suggest that this is due to google actually doing a really good job of filtering the fraud before it hits us.
also being an volume ad middle man in the industry, I can bet what the top comment was referring was price.
adx is the cheapest, because it's the worse. your ad will be seen by users in spots previously occupied by "the banks hate this guy" kind of click bait ads. which have ridiculous ctr!
everyone I run experiments there I keep getting calls from clients to take their ads out of some and some sites before brand sees it. it's a nightmare.
No, not price, although they are pretty cheap and run a fair auction system (unlikely other exchanges...looking at you facebook/appnexus). The CTR on adx is actually one of the better ones, and they tend to have less junk inventory.