The problem is that it is just so tempting.
Say that you sell Vespa scooters in Green Bay. You bid on dozens of variations of “Buy Vespa Scooters Green Bay” in Google AdWords and MSN AdCenter. You sell a lot of scooters. It’s practically like printing money. In fact you figure that for every 100 clicks you get on an ad, you sell a scooter.
Then you wake up in the middle of the night thinking about how you scale the program. You decide to start bidding on terms like “fuel efficiency” and “save gas.”
And the whole program tanks.
So what happened? You dig in and you see that your cost per click jumped from .40 to $3! You realize that you are competing with hybrid car makers and fuel additive products and alternative energy advocacy groups. Your quality score is low because your site is about selling scooters – not fuel efficiency. Your conversion rate goes from 1% to .01% because people searching on the term are much less qualified. They may be looking for scooters, or a hybrid car, or a fuel additive.
The point in all of this? It’s great to test. In fact, it’s great to test hundreds or sometimes thousands of terms. In the PPC world, you let the numbers tell the tale. But in 98% of the cases we’ve seen, “peripheral” terms just don’t work. Your competition increases while your relevance and conversions decrease. So while ongoing testing is essenetial to the success of any PPC campaign, focus your tests on variations of your core products and services, your long shots are, at best, long shots.