PPC specialist
Decides where your ad money goes and watches what comes back. The work is not in launching a campaign but in pruning it every week.
When your project needs this person
As soon as ad spend passes a few hundred euro a month.
What happens when they are missing
The campaign runs on autopilot and spends by inertia. After three months half the budget goes to searches unrelated to what you sell.
How this appears in an offer
Appears as a percentage of spend or a fixed fee. In both cases ask how many hours a month sit behind the number.
What they do NOT do
Not responsible for what happens after the person reaches your site.