A reasonable inference is that: the depth of knowledge on a given subject will vary for every speaker. Even a person who researches and writes a dissertation will not necessarily be an 'expert' on every possible question that might be asked. The key is to know where and how to get more information. On the other hand; if a speaker has spent their career working in a particular field of study I would expect them to know the answer to more potential questions.

What if a speaker cannot answer a question, however, they provided a 'Good' talk. Would inability to answer a question change a talk to 'Bad'? How a speaker responds to a question they cannot answer may point us towards our judgment of that talk. If links, references, or more information is provided then I see this as sufficient evidence that the speaker is qualified.

The topic has some inherent interest for participants and/or the subject is highly relevant/trending. The speaker has done their homework regarding the audience and is qualified to address the topic.

Like many of us; I have attended a multitude of talks at conferences and other forums. This course has helped me answer the question, "Was it the topic or the speaker that made a 'good' v. 'bad' presentation"? I have attended presentations on topics that were highly interesting 'on paper' but the speaker did a poor job. Various incarnations of topics and talks that make for good v. bad presentations now make more sense when viewed through the lense of ML 117.