There I was happily using Lubuntu on my 32 inch monitor with great clarity (well apart from all the screen tearing that is).
Did an upgrade and thought that I needed to put my reading glasses on, but then realised that I was still wearing them. The greyscale antialiasing option had been removed.
Just about everytime blurry fonts has come up on any forum I have seen the answer has turned out to be use greyscale. Oh well I suppose that I can still make out what I am typing. I think!