It might be semi-comforting to retain a Speaker who's very busy. After all, if many other groups are hiring this speaker, he or she must be good, right?

If the speaker doesn't arrive the night before, or at least two to three hours in advance of the presentation, watch out. Professional speakers arrive in advance, work out the room logistics, meet with the production and audio-visual personnel, walk the room, give equipment a test run, and in general make themselves thoroughly familiar with the meeting venue.

No matter how good the speaker might be, if he or she expects to get off a plane, jump into a taxi, and make it to your site with moments to spare, be on guard, for you could get a performance that is not quite up to par or doesn't fit the needs of your audience.