A Google representative works with the goal of increasing revenue for Google. They are paid by Google and work for the company.
An agency or a Google Ads expert works and is paid by the client.
So, the targeting and motivations are clear.
Personally, I always listen to their opinions and decide whether to proceed or not.
Many times they have given me brilliant ideas and directions, while other times they have let me down.
So, everything they say is scrutinized.