Notes from the Google Webmaster Hangout on the 7th of March, 2017.
Google Doesn't Detect Text in Images
Google doesn’t do any OCR on images to detect text.
Fonts Don't Affect Page Quality
The font used for text doesn’t affect page quality, even Comic Sans.
You should link to new pages which are important, from other important pages on your site, like the homepage, so Google understands it is something they should focus on.
Test HTML Parsing Issues with a Headless Browser
Google uses a normal parser to determine which tags fall outside of the head. John recommends using a headless browser or using a W3C validator to check pages.
Manual Action Penalties can be Applied to Sites Made from Thin, Spun or Aggregated Content
Thin content penalties can be applied to sites manually by the web spam team where the entire site seems to be thin, ‘spun’, or aggregated from other sources without any unique additional value.
Duplicate Content Filtering is Query Dependent
Duplicate content may still be indexed but filtered out of search results for queries where it would result in an identical snippet.
Noindex Pages are Dropped Immediately After they are Processed
Noindex pages are dropped from the index immediately after they are processed, however processing can take some time to complete due to technical limitations with Google.
AJAX Content Loaded After 20 Seconds Won't Be Seen by Google
Content not loaded onto a page via AJAX immediately, probably won’t be seen by Google. John says 20-30 seconds is too long.
A High Volume of 301 Redirects is OK
John says millions of 301 redirects are OK and won’t affect your site.