Lack of response to anecdotes and humor, which I use a lot too, is really off-putting. You have no idea whether they've all just switched off / they're only there because they have to be, or whether they're actually listening. It's particularly bad in some cultures like Japan where the attendees are often there as a reward and so use the time to catch up on news, sleep, or just generally not listen, so you can get zero audience reaction, and that's before getting into the translation problems with jokes and metaphors, or the very different sentence structure where you have to say a complete sentence, then pause and wait for the translator to rearrange the words into the Japanese order, then say them, and then you can start the next sentence. Another bad one is where the stage is lit but the audience isn't and/or is well below the level of the stage so you're just talking into a blank void if there's no audience reaction.