The Decline of reddit Self Serve Ads

My first inclination is that it's the influx of Digg users causing the lower returns, however, I don't know if that holds water.

Digg is notorious for providing low-quality traffic, but that the volume is going down doesn't make sense in that regard, as more users should equal more volume, even if the quality of the volume is lower traffic, it should still be up.

This leads me to question whether or not the new Digg users are replacing Reddit users.

Of course, it could also just be to a lower quality campaign, or perhaps ad-blindness as the users have become more used to seeing the ad on Reddit's site? Another possible explanation would be the rise of Adblock amongst Reddit users, of course, but I don't think that number scales enough to be the proper explanation.

I'd love to hear from other Reddit advertisers to see if this is isolated or more widespread.