Data mining and ranking is neither debugging, nor DoS protection or abuse protection, so I don't see how it could be allowed.

The FAQ makes it even more clear:

> Is information about my queries to Google Public DNS shared with other Google properties, such as Search, Gmail, ads networks, etc.?

> No.

I did not mean "my queries" being "shared" but the query collection/archive as a whole. It would be another source to know what domains the people visit.

> And they say that the logs are only used for debugging, DoS protection and abuse.

Source?

Rereading it, I see it's less clear how it applies to aggregated data.