You won't see the actual source, you will see the the machine code. It depends on the language the app has been compiled with, if the app uses .NET then you can see most of the source pretty clearly with ".NET Reflector (

" ). Though if the application has been compiled w/o any usage of .NET theres no way to get access to the actual source. To answer your question, AV's are mostly right, and mostly false. There is no 100% guarantee that the application is clean even if the AV says it is, it still doesn't mean that it is. It's simple, don't simply download/run applications from random sources, but if you feel that you must test them then use

.. in the end you just shouldn't download from random sources.