@Dijkgraaf Thanks for the info (and link) on Google's + / "..." change - I'd missed that!
It does seem that more and more sites are attempting to add text with no visibility to their pages. Sadly, it seems to be working very well for those that choose these methods.
Also remember, however, that good long term ranking is also dependent largely on inbound links, particularly for pages in a competitive market. Having a lot of hidden text that no-one gets to see is not going to help this. Google might give a boost to new sites posting lots of keyword rich content(?), but unless they can follow this up with some inbound link popularity then they are not necessarily going to stay at #1 for very long (in my opinion).