Right.
So it turns out that the visual studio/.net convention of assembly.extension.config for config files is NOT to be used for your own devices outside of visual studio.
Example:
Today I made an app called whatever.client.exe. It needed to read an xml file for some config, but I didn't want to use Visual Studio to generate that config, and I didn't want the Properties.Settings.Default stuff, for reasons beyond the scope of this post I just wanted to load the xml config file and parse it myself.
Easiest way to do this I thought was name it whatever.client.exe.config and load it...