Is there a way to verify that a search result set is “unpersonalized?” I wouldn’t put it past Google to be able to track you even into an incognito window.
Even the most paranoid don't think it's profitable for Google to track you through Tor, even if they've found some exploitable weakness. Try your search via Tor. Browser fingerprinting will get them little distinguishing information beyond what they get knowing you're coming from a Tor exit node.