At a meeting tonight, there was a brief side conversation started by me about a presentation we all had attended. I wanted to know if the PowerPoint had been easy to read, given that room lighting can have a horrible impact on readability. This led to a discussion on how much text should be on a slide. Needless to say that my view was very different from others at the table. In recent years, I've given presentation (and classes) to groups that contained people who spoke English as a second language. I've also given presentation where the printout of the presentation was the handout (a standard practice with many of library councils' training programs). And I've given presentations where they have had a second life online, which means that people need to understand the slides based on the text that is on the slides. And -- like you -- I've read people presentations online and based everything I know about what the author intended on what was presented on the slides.
In my mind, having too little text is as dangerous as having too much text. I want enough text so people "get it," but not so much that they glaze over or become confused. It is a delicate balance. It flies in the face of correct presentation design, yet it works. For example, I've been studying a presentation done by Richard Fyffe in December 2004 (entitled "Digital Preservation:Theory Approaching Practice"). There are likely too many slides and too many words on each slide, yet we get his message without hearing him.
The same is true often in the online environment (web pages). We need to give people enough text so that they understand what we're talking about, but not too much per page. Better to break up text over several pages, which can make it more readable online. (The same is true with PowerPoint.) Unfortunately, many library web sites say too little about their services, how to use materials on the site, who to contact, etc. Instead of telling people what they need to know, we let them fill-in the blanks and hope that they do so correctly.
By the way, Steve Cohen and others have started using blogs for presentations instead of PowerPoint. I've not tried it yet, but need to find time to test it out. Gary Price uses web pages for his presentations, which works well with his style.