I hear you, but if I'm looking at your code that I didn't see you write in front of me, how do I know that code really came from you? You could have copied and pasted most of it from somewhere else and only made slight changes.
Well if it's an open source project, you could just google some of the code snippets and find out.
Plagriarism isn't hard to detect unless the code is proprietary.
Then I suppose you either have to be paranoid and suspect everyone or accept that most people you talk to are pretty much like yourself and not lying cheaters.
