According to SC Magazine article, "Significant" security threats found in Android devices", those Android phones that you're purchasing off the shelf, may contain security breaches.
(SC Magazine provides information security profesisnals with the in-depth technical and business information they need to tackle the countless security challenges).
These compromised phones include Samsung and Motorola phones.
The apps they come preloaded with, don't explicitly request permission from you, the user, to access personal information and phone features.
Thus making them vulnerable to attacks from hackers who can bypass the phone's security mechanisms and wipe out your data or record your conversations.
Please read the above article, to find out which model phones have the problem, so that you don't purchase these phones until Google fixes the problem,ok? :)
Article "Significant" security threats found in Android devices, by Angela Moscaritolo, SC Magazine, December 2,2011.