How can we know how profitable our campaigns?

With all of us marketers (newbie through pros) clicking on each others' adwords ads all the time, how can we know how profitable our campaigns really are when we setup adword campaigns for our sites?

Are aware of how many of our paid clicks are from targeted visitors looking for our product vs clicks from other marketers spying, researching and testing in our markets?

That's why you need to use some sort of sale/lead tracking software for all ppc ads. If your worried about click fraud, you could always go through your logs.