A WebmasterWorld thread has one webmaster complaining that Microsoft is hiding the user agent for the spider, BingBot.

The webmaster said:

So either Microsoft has a weird bug, someone is spoofing the crawler in a weird way or Microsoft is doing this on purpose?

I should note, I did not check my log files to verify this on my sites. So I am going with “zerillos” post and with no back up evidence.

However, Microsoft is known for their crawling issues. Most recently, crawling too hard, updating IPs and many more. BingBot is pretty new, coming to us just over a year ago.

Forum discussion at WebmasterWorld.