Yes. When you create (or edit) a Metric Alert, you choose the level at which the condition is evaluated:

  • Account (default): the condition applies to the account total.
  • Campaign, Ad Set or Ad: the condition is tested item by item, and the notification tells you exactly which one fired. For example, "CPA > US$50" at the ad level lists the ads that went over, from worst to best.

Only items that had spend in the period are evaluated, so anything that didn't run doesn't trigger a false alert.