Everyone has different reasons for wanting a ppc management service, so everyone has different expectations and results that they are looking for.  You can always call and talk to someone at a service, and tell them what you are looking for, and the kind of results that you want.  Also you should make sure you compare pricing, and even get a couple proposals if you like.  There aren’t long term contacts, and just because you get a proposal doesn’t mean that you have to choose that service.  Since everyone has different reason to get a service, and different expectations, not everyone will have the same service that is right for them.