First, be aware that our systems take time to adjust to your changes; it may be several days before the full effects of a recommendation implementation, positive or negative, can be seen.
We have strong confidence in our simulations; but we watch implementations closely to determine whether there's skew in results, and whether we need to alter thresholds. We don't believe there are situations in which one of our recommendations will result in a loss of revenue, but if you have an example case, we're interested in hearing about it.
Some of our recommendations have side effects; increasing the size of an ad, for example, might cause the page it’s on to be redesigned, and the page redesign itself may negatively impact user interaction. We can't simulate secondary effects caused by changes to the page itself. We are being as careful as we can, and you can always reverse the change you’ve made.
If you wish to undo a recommendation, and we haven’t already detected your implementation, go ahead and reject it by clicking the No thanks link, and tell us why. If we’ve already detected the implementation, we’ll detect the fact that you’ve reverted that implementation, too.