Update: I checked our display ad viewability report and 41% of impressions ran below the fold
We pulled our Q2 display report on Monday and the viewability number came back at 59%. I dug into the placement list and the majority of the weak spots were cheap display spots we added in March to hit a volume goal. Our media buyer ran it by the vendor, who basically said that is just how those placements work. We cut the worst 12 placements on Wednesday and CPM went up $1.80 but the click-through rate nearly doubled. Has anyone here had luck pushing a vendor on viewability guarantees, or do you just keep the blocklist running?
Got a vendor to move on this once by showing them we'd cut spend unless they added a floor. They agreed to a viewability minimum on the next insertion order, and the cheap junk spots got dropped from the default list. Takes some push but it worked better than blocklisting alone, have you tried putting it in the contract itself?