Originally Posted by starrigger
On your statement "Don't use Word," I say, not true. It's all well and good to say build the formatting from ground up in Sigil or whatever, and that's fine if you have endless time. But most authors want to get back to their writing. The fact is, you can build perfectly good ebooks using Word (the Smashwords Style Guide offers many useful tips), if you are careful with styles and are willing to tweak a little as needed. So the CSS isn't quite as clean as you would like. It still works, and if done carefully works very well.
As for Word, that's another kettle of fish. I've seen cases where the eBook looks not bad by default but has underlying problems. Such as not being able to go into night mode on a tablet, not being able to change the font size and not being able to change the font.
Word puts in font family where it doesn't belong and incorrectly for an eBook. You get color codes that don't need to be there. You get other mess that in some reading apps can be a problem as they aren't as tolerant of things like some of the codes Word sometimes puts in in the main text as ADE is. If the code didn't have those (not part of ePub) codes, then those apps would work fine.
Next time you have a Word document converted to ePub, use an iPad and Android tablet with the popular reading apps (iBooks, Bluefire, Stanza on iOS and Aldiko, CoolReader and others (not really up on Android reading apps) on Android) and tell me if everything works perfectly. It may or it may not. It's a crap shoot.