I have tried
7z a -x!.\o -x!.\*.exe -x!.\*.zip -x!.\summary.* -x!*.bak -x!do7z.* -x!*.pdf df.zip
and it disobeys about the pdf's and several other things I also tried -x*.pdf and it won't remove the pdfs from all throughout the file (maybe it's directory-specific? manual does not say).