Originally Posted by DiapDealer
I never ran into a situation where HTML Tidy (in Sigil) resulted in the "loss" of any well-formed, valid, ebook-typical xhtml.
That's the point, surely? If you write good code, you don't need Tidy. But bad code might lose data.
Back in the dim, ancient history of EBook conversion (i.e. a year or so ago :-) when I was still kidding myself that automatic conversion from complex Word or Quark layout was feasible, I was trying to tame VERY messy code - and more than once lost text.