Sgt_Kickaxe - 10:08 am on Oct 23, 2012 (gmt 0)
I suspect that taking the code at face value became a problem when platforms like wordpress and drupal became popular and templates became readily available everywhere. Those templates were used by many different language sites yet the templates often had the same(wrong) language specs within the code.
This applies to more than just language specification, imo, and I'd be very surprised if there is anything at all that Google takes at face value from within the code save for perhaps rich snippets as an "extra" (not a ranking factor but an added feature). Even rich snippets are finding their way into templates and addons that are widely used.
- minimize sitewide boilerplate
- one language per page only
- clear definition between sections if a site is multi-lingual