@Harry Tuttle: I always look for the GPL licence.
"Sadly, most of the rest of humanity, seem to have very little interest in the source code behind the software they use."
Whilst I agree with you regarding open source, most of humanity doesn't have a clue what source code is, and wouldn't understand the, what would be to them gobbledygook, should they view the code anyway. And how many of them would be able to interpret and correct compilation errors? The majority of humanity are consumers, not coders or IT experts.
Google need to vet applications before making them available for public download. Yes, this takes time and effort and as a result has a financial impact. But it's not like Google are struggling for funds.
I do trust open source software above closed and proprietary code, as should the rest of humanity. And whilst the Apple way of controlling applications is extreme, it does have it's merits, such as the trust of the consumer.