While it's satisfying to fix with a block, or vent in a blog post or tweet, actually getting to the bottom of the issue with the MS crawl team can fix the problem for other sites, too -- so that's the most civil and community-spirited response.
When you think about it, bing/live/whatever it's called today sends very little traffic, and the crawler to get that traffic has a long history of what you call bugs. The cost-benefit analysis IMHO points to too much cost for really zero benefit.
Hence why many webmasters block MSNBot.
"I am a Program Manager on the Bing team at Microsoft, thanks for bringing this issue to our attention."
Have to give them credit for that.