After a month of running several successful campaigns with adCenter, I decided to pare down the static creatives in one of my campaigns.
One creative, in particular, outperformed the others quite handily.
Prior to deleting the under-performing creatives, 99% of my keywords had a status of "approved". After deleting the underperforming creatives, 50% of my keywords acquired a status of "pending approval".
These ads were not dynamic in any way, shape, or form (ie. I was not using parameters in this campaign)...yet, somehow, the keywords were assigned to specific static creatives. Some of the creatives differed from others by only a single word (ie. "get widgets now" vs "buy widgets now")....but, apparently, keywords are associated with one or the other, not with both. So if you delete a creative that a keyword is "associated with", the keyword loses its status and the approval process begins anew.
It'll be interesting to see how this affects traffic. Hopefully the approval process won't take the 3+ weeks it took last time.