My friend Judith gives this interesting blog post about the facilitated session gone bad. It's her honest assessment of a mystery association's planning process. As the ones who hire facilitators/consultants, we sometimes underestimate that what consultants say they need, they actually do need; or when clients/groups say to their facilitator they don't need/want something, they actually do.
Her 6 points: (read the post for "how to" details)
1. Plan ahead
2. Develop a background packet about your organization
3. Develop a written statement about meeting expectations
4. Groups need action steps
5. Develop a job description for the consultant you're hiring
6. Spend a few face-to-face minutes with the consultant prior to the meeting
A few notable points I found in there too: a) always need to ask more than once if there's anything happening you should know about; b) be sure they have the food situation worked out (where and times); c) have your own back-up plan for any equipment you might need - but isn't there.
This is interesting case study for anyone who facilitates/consults; as well as for those who hire consultants.