@slowsmile: ADE pagemaps are an Adobe extension and books that contain them won't pass epubcheck. They're actually not that common.
The NCX page tables that KevinH referred to are (epub 2.0.1-compliant) page number tables wrapped in
<pageList> tags. They're rarely found in epub2 books because only some DAISY-compliant apps support them. (BTW, they are supported by the epub3 output plugin.)
Since they basically use the same syntax as TOC entries they also might contain fragment ids.
If you don't want to deal with them, simply check for the presence of <pageList> tags in toc.ncx and display a warning.