Valimail, a US authority in online authentication, has released the results of a study conducted on the ability to spot false election campaign material sent via email. It has found that only 20% of a group identifying as Republicans identified a fake sent by their candidate, compared to just under 40% of Democrats.
https://www.notebookcheck.net/Most-US-adults-can-t-tell-real-election-campaign-emails-from-fake-new-study.355196.0.html