Also, its likely that inline styling will override the viewer's stylesheet as it always overrides internal CSS stylesheets and the <style> sections in the HTML file's <head> section.
I've seen ebooks where every paragraph tag is styled. Such books probably can't be "fixed" without editing an ePub or AZW3 version and bulk replacing all of the <p andWhateverStyle> tags with simple unstyled <p> tags.