Again, might be an EU thing, but even my logged-out youtube sessions seem completely un-personalised (I likewise use sites in fresh sessions by default).

Opening youtube.com in a fresh, logged-out browser session gives me a blank home page, with this dialog:

> Your YouTube history is off

> You can turn on watch and search history at any time to get the latest videos tailored to you.

> To update your selection, turn on YouTube History and confirm your settings to accept the use of cookies and data