Article discusses problems with app security on iOS, but the principle applies to others as well
http://www.troyhunt.com/2011/10/secret-ios-business-what-you-dont-know.html
In the beginning, there was the web and you accessed it though the browser and all was good. Stuff didn’t download until you clicked on something; you expected cookies to be tracking you and you always knew if HTTPS was being used. In general, the casual observer had a pretty good idea of what was going on between the client and the server.
Not so in the mobile app world of today. These days, there’s this great big fat abstraction layer on top of everything that keeps you pretty well disconnected from what’s actually going on. Thing is, it’s a trivial task to see what’s going on underneath, you just fire up an HTTP proxy like Fiddler, sit back and watch the show.
Let me introduce you to the seedy underbelly of the iPhone, a world where not all is as it seems and certainly not all is as it should be.
http://www.troyhunt.com/2011/10/secret-ios-business-what-you-dont-know.html