Lately I will see good stats for a few hours, think Im making money, then I will blink and FB will more that double the reported impressions cutting my CTR in half. Since Im bidding CPM, this fucks me hard. At times Im seeing clicks with 0 impressions. Other times the impressions are grossly over-reported. Ive had campaigns that had run half the day with a modest ROI go $400 negative in the 15 minutes it takes FB to refresh the stats.