Don’t Delete Poor Performing Keywords in adCenter
Keywords with poor performance should have their CPC set very low if you don’t want to spend money on that keyword anymore. When you delete a keyword from adCenter its entire history gets removed – even its cost is deducted from the ad groups total cost. There is nothing at all to tell if a keyword ever existed in an ad group.
Now imagine if you delete poor performing keywords when you have spent £20 on them and poor performing ad groups at £100. Every time you delete a keyword it will deduct £20 from the total expense of that particular ad group. The ad group may never show as reaching £100 expense! You could be letting really poor ad groups run and run as adCenter makes you think you have not spent that much money on them.
This is very misleading and hopefully its something Microsoft will fix soon.