not2easy - 3:16 pm on Dec 19, 2012 (gmt 0)
They don't make it easy to find information at bing. But I did find out they don't count well:
Bing operates three crawlers today:
Bingbot is our standard crawler and handles most of our crawling needs each day. Adidxbot is our Bing Ads crawler and is responsible for crawling ads and following through to websites from those ads for quality control. MSNbot was the name our old crawler before Bingbot arrived on the scene. Msnbot still handles some multimedia and feeds crawling duties, but will retire soon. Bingbot will take over all Msnbot duties at that time. Finally, BingPreview is used to generate page snapshots.
Edited to add: They say Page snapshots comes with Windows 8 "to bring new crawl traffic to sites" via the preinstalled Bing app.