aristotle - 4:39 pm on May 13, 2010 (gmt 0)
Elsewhere, at least 2 people have established poor previews are caused by blocking CSS in robots.txt- the logic being Google cannot create a "snapshot" without the style sheets. I expect image folders and other resources that are sometimes witheld from bots will cause similar problems
Thanks for this information. No css for this site is blocked, but I have blocked most of the images to prevent a flood of unwanted traffic from Google Image Search. I may unblock the images for one or two pages as a test to see what happens, although I think I might have to wait a while since Google's image indexing can sometimes be slow .