Troubleshooting BadImageFormatException

After I stopped banging my head on the desk thinking of the entire week I spent running down this problem, I am sharing what worked for me. I have Win7 64 bit, 32-bit Oracle Client, and have my MVC 5 project set to run on x86 platform because of the Oracle bitness. I kept getting the same errors:

Could not load file or assembly 'Oracle.DataAccess' or one of its dependencies. An attempt was made to load a program with an incorrect format.

I reloaded the NuGet packages, I used copies of the DLLs that worked for others in different apps, I set the codebase in the dependent assembly to point to my project's bin folder, I tried CopyLocal as true or false, I tried everything. Finally I had enough else done I wanted to check in my code, and as a new contractor I didn't have subversion set up. While looking for a way to hook it into VS, I tripped over the answer. What I found worked was unchecking the following:

Tools
-> Options
--> Projects and Solutions
---> Web Projects
----> Use the 64 bit version of IIS Express for web sites and projects

Verified build settings such as Platform Target are all the same (x86).

That's not what the crash log says:

Assembly manager loaded from: C:\Windows\Microsoft.NET\Framework64

Note the 64 in the name, that's the home of the 64-bit version of the framework. Set the Target platform setting on your EXE project, not your class library project. The XxxDevicesService EXE project determines the bitness of the process.