How do journal editors check word count on pdfs? I've read posts from journal editors on Academia Stack Exchange that the first thing they do is check the word count of submitted articles.

How do journal editors check the word count of submitted articles, considering that authors may submit articles in pdf format with numerous tables and figures?

To check my own articles, PDFs produced in LaTeX, I open my PDF, select all, then copy-paste into Microsoft Word. This method overestimates the number of words since it includes all page numbers and all numbers inside tables, but I prefer it to TeXcount (http://app.uio.no/ifi/texcount/online.php) since it includes references and bibliography.
I suspect that in many cases where the authors submit a PDF and the editors do not use Linux (as may be the case in many disciplines, including most arts and humanities disciplines), that an exact word count may not be obtained. Instead, an approximate word count based on the length and formatting of the manuscript can be determined.