Visual aids that do not work are without a doubt the biggest problem with technical presentations. Audience feedback is not what it should be in most presentation situations, and most of the time the speakers do not realize that most of the audience could not see his or her graphs or read the data tables. Most times, people put too much on a visual aid; sometimes there are just too many. Sometimes they are unnecessary; sometimes they are just sloppy. Most oral presentations are not edited, and the audience becomes the testing ground for visual aids. When they do not add value to a presentation, they usually produce a negative audience effect.