Most PDF files found on the Web have compressed and unreadable data streams. Is it possible to uncompress the internal content of a PDF file using Acrobat or Acrobat Distill
With Adobe Acrobat you can get at the internal structure after profiling a PDF (preflight with some profile (e.g. detect PDF syntax errors), then Options->Internal PDF structure) - but there's no way to get something editable with a text editor.