I have argued in the past that slides dense with text should be avoided. And this mistake is by far the most common one I see. But I also have seen the opposite and a recent presentation was an example. The slide contained a paragraph of text (it was quoting a document, so it was OK to have a paragraph), but it was in what appeared to be 14 point font and only took up the top one-third of the slide. The bottom two-thirds were empty. It made the slide look out of balance and the text was nearly impossible to read. White space on a slide is necessary, but if you have too much, it will look strange. It would have been better to increase the font size and vertically center the text on the slide to give it balance. If you have a small amount of text on a slide, try to use a larger font and position it in the center of the slide so that it looks even and not lopsided.