I have a collection of PDF files which I'm looking to load onto a Kindle. First, however, they need to be converted.
Experimentation gives sub-par results by selecting and converting to mobi through calibre. Better results are achieved by copy/paste to a text file. I haven't yet tried a bulk convert to text from calibre.
Some PDF's have very odd results, where what's visually and logically a paragraph of text is somehow "columns" either when copy/pasted or converted. The result is a sort of interlace, but slightly out of sequence. However, that's unusual. For the most part/copy past gives excellent results.
These PDF's generally are all text, with footnotes.
It's a bit mystifying why copy/paste would be better than calibre converting to mobi.