Consider the difference between a minified JS script or one produced with emscripten and the code pre-minification. One is unintelligible guaranteed, the other … maybe haha.
Unfortunately, what tended to happen is people would write one liners, and slowly expand the one liners into more complex one liners, and then integrate them into larger scripts without refactoring. Regex can triple that problem (thankfully Perl 6 allows you to write some of the most intelligible — seriously! — regex out there).