I have stopped using WordPress for personal projects and only use it professionally any more.
In case you haven't been aware of this, WordPress core developers think that potentially breaking thousands of links on thousands of sites is an accepatable edge case. Here's a great summary of what has been said.
I have another equally stupid pet bug. Basically, a CSS file can break core functionality which can lead to bugs in plugins like my theme switching plugin. It's a rather rare bug but the sloppiness of the coding is on the same level.
I have a code-centric blog. I post a lot of code, and of course readers post code themselves from time to time. Of course WordPress has to mess with comments as well. I realize that removing potential XSS code is a good security measure. But seriously. Do not delete any content before it goes into the database (besides SQL sanitization). I can't even recover that comment now.
WordPress rant over :-(
Oh well, I'll just keep updating this post with some gems I find
Seriously? Check for yourself in the source: wp_check_filetype()<?php /** * Retrieve the file type from the file name. * * [... there's really no need to show the rest...] */?>