Why might some presentations be well-researched, yet fail to make an impression on the audience?

well from what I see/hear..,

Explanation:

Sometimes the audience judges you by the way you speak (slow or fast) and it'll be hard for them to hear your correctly and might think you said something different from what you really said. Your presentation might be boring to some audience by using the same word over and over again. Not holding back your feelings can be part of it too (like anxiety and emotions)