---sorry for my bad english
---
i think u have to detach Character-Styles to the text-passages that are italic/bold/etc.
then export it and the style attached to "span"-tags won't be generated-style anymore but the character style u had given to it.
Some other Spans are created because of "bastards" (donno if it's called like that in english...) in your paragraph styles.
me always find/replace text passages that are italic/etc. and attach a character-style to it. so the bastards shouldn't be there anymore.
hope that's helpful... lol