If this ad agency's KPI was clickthroughs, not conversions, then I'm pretty certain this ad is getting results.
Unfortunately, of course, once users realise they've been tricked, their instant reaction is to close the site in disgust. The last thing on their minds is even LOOKING at whatever it was the site was selling.
One could argue that the agency was doing nothing wrong - their client probably demanded clickthroughs as KPI, and on this, I'm sure they deliver. But the reaction after click-through in no way helps their client.
An agency that cared about their client would realise that what the client (and every client, really) wants is conversions. Yes, an ad banner cannot guarantee conversions. But if the banner pisses off the users it brings to a site, you can bet it'll guarantee a lack thereof.