One thing I've learned is people will always remember how you interact with them.
I'm sure it happens to all of us, where we send the tech rider to our clients, they confirm that the tech and A/V needs are available... only to our horror that isn't the case at all when we get to the venue.

1.) it is frustrating; but no matter what, I can't stress enough how important it is to keep a positive attitude and express it.
Smile, always smile. "Its ok, we can find a solution".
Your client is probably more embarrassed that the venue/themselves did not deliver on their end. They knew they messed up.
It does you absolutely no good to express your frustrations.
After all, our clients hire us to problem solve, not to problem complain. Keeping a positive vibe can smooth over a lot of the frustrations that's felt equally by the person who's cutting you the check.

2.) Seasoned pros know this ,but if you are a newer performer, my friend, always have a back-up plan (whenever you can, bring a back-up microphone/head-set/DI box, etc...).
So you can actually problem solve to your best ability.

Every now and then I'll hear stories from clients who told me their entertainers previously were grumpy and difficult to work with (when I suspect its prob. because the client/venue didn't deliver on their promise in the A/V needs); its unfair, but a lot clients will put unpleasant performers on blacklist forever because of one bad interaction
So remember; always smile, problem solve, and not problem complain.

Some good advice here. I regulary think about his quote above as it is more true than most performers will ever realize. One of the things I wish all entertainers could do is spend a few weeks at an entertainemnt agency as we regualrly hear exactly the information you mentioned above - the problems they had with so and so, this guy and why they didn't like him, and many other problems, criticisms and compaints about other performers and experiences they have had in the past. Yes, we also hear about the ones they enjoyed and might have back, but they are much fewer and far between.

Quite frankly, I love it when this happens for several (to many) reasons as it allows us to know more about the client, their likes and dislikes, and how we can best position ourselves to serve them. Also how to avoid these issues and problem areas. There is a lot to be learned from this. Also you quickly realize that only about half of the problems and complaints are about the previous performer's show or performance, the other 50% or so is about them, the way they do busienss, they way they treated staff or audience members and several other key factors.

Once a client has this perception about someone in their head, it is next to impossible to change it or gain another chance with them (whether their perception of valid, right or wrong). This is often one reason why they turn to agencies.

When you have done enough shows, you know that everything said above is 100% true.

In my book, "Dick Oslund -- Road Scholar", I wrote up "a bunch" of the sort of problems that Nash described. --and, I talked about how I handled many of them! Some problems were "nobody's fault". Others were caused by sloppy school administrators.

I always figured, "I'm here for 45 minutes!" So, I did the best that I could do, and, often, "things" worked out.

My manager would often "send me in" to "square the beef", when a previous program hadn't "delivered".