With reference to this post
I was doing that this week too. Kept getting streaks on windows where it is easier to do straight pulls. Changed the channel, the rubber, technique and nothing fixed it. Was getting fed up so buffed them up with a microfibre after they dried. Took me ages. :
Ian do you think your problem might have been caused by what Squeaks has posted below
Oh yeah, my time loser...crap squeegee rubbers. 
I use Ettore rubbers, so theyre soft, I gotta say I have had this problem occuring far too often recently, its almost like one side of the rubber is fine then the other side when its turned over is crud.
I get my Ettores from windowcleaningwarehouse.
What say you ?
Matt