Let's face it; most audiences are bored by PowerPoint presentations. This makes them less effective. This is less surprising when you think that most presenters don't stop to think who their audience will be. Because it is so easy to save presentations and to use them again, PowerPoint encourages us to thinking it's OK to simply re-use the presentation we used last week.
Corporate house styles with standard templates encourage the view that all presentations should look the same and sound the same. This can support the view that the audience should have what we want to give them, not what they want or need to hear.
Take something as simple as the title slide. It often has just the title, the speaker's name and organisation. However, even your first slide sends out a message and may turn off your audience before you start. Compare the following slides:

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The first slide uses a formal font, emphasises the speaker's academic title and qualifications and even without the title sends out a clear message which says "Be impressed by my expertise and qualifications".This may be appropriate for some audiences, e.g. a medical or academic conference presentation. In more informal circumstances it may irritate an audience and lead them to think, "Who does he think he is?". They may be more open to the second style, which is designed to make the audience feel the speaker is one of them and remove barriers. To be effective, you need to consider who your audience is.