Google might decide to use just about any bit of your data to show you ads.

Their terms of service say they could.

You can't verify that they won't.

They won't tell you if they do.

Many of Google's data pipelines are more conservative and privacy-preserving than outsiders might realize.

But Google also reserves the right to tweak any of those at any time, and you'd never know.

The Terms of Service are designed to be as broad as possible.