Quite possibly the world’s worst-labeled option on a WordPress plugin:
What you might assume, as I did, is that setting this option would enable HTTPS to be used on the entire WordPress installation and that it would make the site exclusively HTTPS-based. And you’d be wrong, too.
Instead the option really means: “If you set this, you have to explicitly mark each and every post you want to be secured by HTTPS. Your entire site will now remain completely HTTP-only.” And somewhat snidely, it might add: “Thanks for defeating the purpose of this plugin!”
Now, I can’t imagine who would actually want to do that, and/or what their site configuration would look like. But HTTPS always seems to me to be an all-or-nothing proposition and this mis-labeled option only led to time wasted looking for a culprit in the .htaccess file, in the mod_rewrite rules, the wp-config file, and elsewhere.