Just popping in to +1 on this thread.

I've got easily noticeable streaking in the browser (esp. its startup screen), where a vertical line of pixels (about 1/3 from the left) form the basis of the streaks (others have explained better!). So scrolling vertically whilst in portrait might not be so dodgy-looking as the streaks stay in the same place relative to the text, but scrolling vertically in landscape is like having a bad amiga demoscene effect going on in the background.