I saw some flakiness in which a DevExpress namespace could show up and the appropriate .dll was in the bin folder yet the project wasn't referenincg the .dll!

It happened with DevExpress.XtraPrinting.v15.2.dll and I had to manually add the .dll as a reference to get the code to understand the PrintingSystem type even though the namespace was looped in OK. Messed up! You can't just type in some nonsense in a using declaration and expect C# to compile, you have to use a namespace that really is a namespace, but how does C# know of a namespace outside of the references? Is it crawling the bin folder and using what it finds to halfway work in a misleading way? WTF? Maybe a different DevExpress .dll depends on DevExpress.XtraPrinting.v15.2.dll which was why it was in the bin folder to begin with (as I didn't put it there) and... You know what, I bet a namespace is split across two .dlls and I had the ineffective half to start with. Maybe that is what is going on. Nasty.