If what you mean is using a background in a spread; make sure your image is the right resolution (300 dpi if you are printing, 96dpi for screen resolution).
Regarding the contrast, make sure your image is not too dark if you are using black type, or too light if you are using white type.
Recently, I had an issue with a corrupted font, and my text displayed corrupted in the final artwork (only the text on top of the image was displaying wrongly!). Very strange... Converting the font to paths solved the issue. The printshop paid for the second print, as the final PDF was looking perfect.