If you are running a Click Ad campaign (Pay-Per-Click, such as Google AdWords), a key question is, are you budget limited?
If you have a daily budget and it is running out before end of the day, you are spending too much per click.
This can be very dramatic. We've seen people pay more than three times what they needed to per click.
The main reasons and remedies are:
Sometimes you are trying to spend as much as possible - usually in a situation where you are selling a high end item to a limited public. In all other cases, the ideal scene is for your daily budget to run out at one second to midnight every day.