Nine times out of ten the presentation results of Powerpoint are lousy because the user doesn't follow any rules and has no idea what a presentation should look like. I worked for a major airline on a secret presentation about the restructuring of the ground labor force. It took three years for me to convince management not to put every word of the presentation on the slides and the need to use compelling graphics and pictures. Needless to say in three years we went through a lot of versions. I'm quite proud of the end result. I'd show it to you but I can't (I signed confidentiality papers.) Although over a 100,000 airline employees did see it.
Seth Godin has written a great list of rules for Powerpoint users. Check it out. http://sethgodin.typepad.com/seths_blog/