I was wandering seeing as Google and others keep trying to get more and more 'human' in terms of rating whats good and whats spam, is it known if they take into account the size of a heading ie. an thats font size is 40px is going to speak allot more to the user than a thats font size is 14px..

similarly does placement factor ? ie. a 300 word article at the bottom of a landing page (not in the footer but bellow the useful content) would just be there for seo purposes.

i know they look at if your doing things like text-indent:-9999px; and white text on a white background, but what about these more border line practices that both have legitimate uses but also the possibility to be spammy