Download this good tool called "lutz roeder's .net reflector" from the link below
Using this one could load a .NET assembly and decompile it to see the source code and do something more. I saw this tool being used in one of the C#3.0 Nuggets (I think it was in Object Initializers video). This could be used to understand how compiler takes in our source code and modifies it well!
I knew unused variables in your source code would not be included but it was something really fun to check it out.
I gave two unused variables and a used variable and when I decompiled the code, I found the two unused variables not mentioned at all! there is the proof!