Power adapters and cell phone chargers are also quite common spy cameras. People don't usually suspect such devices to hide cameras, considering their small size and intricate construction. Even if you do notice a glare or something similar, you might pass it off as a part of the design. So they indeed make up for pretty nifty spy cameras.
On the power adapter, you could spot the camera tucked into the hole between the + and the -. Although depending upon the imagination of the camera developer, it could be well-hidden anywhere in the adapter. You just have to scan meticulously. In cell phone chargers, on the other hand, look for any round or rectangular space that could provide room for a tiny camera's vision. It'll be tough to find it, but totally worth the time.