Is there any consensus on the proper behavior of invited speakers?

Earlier this year at the Translating Realism  conference I was pretty blown away by Adrian Johnston. Part of it was his talk (which, with the Q&A, lasted two hours but seemed like fifteen minutes), but a lot of it was just his behavior as an invited speaker. He went to every talk in the conference, participated helpfully in discussion throughout, and every single evening ate dinner with graduate students and other non-keynoters. 

As I've been thinking about it these last few months, it occurred to me that maybe there's something wrong with a discipline where I and others found Johnston's behavior so surprising.

I've been to so many conferences where the invited speakers' behaviors are somewhere on the gamut from not showing up for anything other than their own talk to showing up for some talks but studiously avoiding the grad. students in the evenings. Further along the line is one very well known philosopher who I will not name who makes a club of about 10% of the conference goers and excludes everyone else (people tell me that there are always two conferences with this person).

At a recent conference I went to the two invited speakers skipped all of the other papers and then during theirs regaled the conference goers every day with tales of their shared culinary excess during the evenings where they'd together ditched the rest of us. I found this a little grating at first, but also had some sympathy. Academia is weird because it involves so much public performance, yet tends to attract so many introverts. As an introvert, I find just attending conferences to be almost unbearably exhausting; keynoting would reduce me to an Egon Schiele model. And the kind of people that keynote one conference are usually doing it at lots of them. This must be absolutely enervating for many of the personality types drawn to academia, so perhaps Johnston's behavior really is just supererogatory. 

I don't know. Are there any disciplinary norms for this kind of thing? Any other ways that invited speakers might be routinely falling down on the job?