dstiles - 10:26 pm on May 26, 2011 (gmt 0)
The worst part of yandex, as far as I am concerned, is their poor distribution of bot IPs. Last year I discovered 96 groups of bot IPs, mostly in 1's, 2's and 3's.
Of those, 4 seem to be persistent imagebot groups (ones that get image links by reading pages), which I block with a 403 (mostly robots.txt blocks image folders anyway).
I do not doubt that images are also gleaned directly from their text bot crawls but then, bing and google do the same so I'm not going to go overboard, especially as my server cannot block image access.