First, It's always helpful if you tell us what version of InDesign, and what platform you're running. With new technologies like EPUB export, there has been much progress from version to version. The InDesign Help system covers only the basics of the export dialog. It doesn't tell you the details of this very different workflow which requires quite an education. Apparently, you imported PDFs of each Microsoft Word page into InDesign. InDesign will accurately preview each page, and will pass on the text accurately when you make a new PDF file. However, EPUB export is a much different animal. A placed PDF file is considered a graphic, and it will be rasterized upon export (you'd have the same thing happen if you placed an Illustrator file). The image resolution is set either in Images section of the Export EPUB dialog box or alternatively (if you have InDesign CS5.5) it can be customized in Object > Object Export Options. If you are using InDesign CS5 or earlier the image resolution default is 72 ppi. If you are using InDesign CS5.5 or higher, you can set it as high as 300 ppi. The result is that your text is probably displayed as 72 ppi, explaining your results. You're taking a totally different approach than 99.9% of EPUB creators. There the expectation is that the text will reflow from page to page, and will be able to be resized in the EPUB reader. Your pages would be fixed size which will look lousy on most EPUB readers. For you to understand more about EPUB, I highly recommend a couple of sources. The eBooks of Elizabeth Castro are highly recommend. In particular, "EPUB Straight to the Point" would be good, because it describes both a Microsoft Word to EPUB and an InDesign to EPUB workflow. Here is here website link: Formatting ebooks - EPUB Straight to the Point I don't usually recommend this but it might actually be better to export directly from Word. If you choose an InDesign route, I also recommend Anne-Marie Concepcion's videos on Lynda.com.
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