Here's a personal tale of irritation that might cause others something of an ah-ha moment.
My last 2 smartphones (a recently retired HTC Aria and a brand-new Galaxy SIII) were both shipped with 5V 1A wall warts for charging through the USB socket. Being on a standard post-paid plan, I've has the Aria for a full 2 years and have just recently upgraded to the SIII, and thus the HTC-provided power pack, being nice and small has lived in my briefcase for charging on-the-go.
The new Samsung charging unit, being even smaller, was destined for the same usage.
In order to gain some flexibility, I bought a couple of seemingly similar wall warts from Catch of the Day a little over a year ago. I left these plugged in at home or the office as permanent charging supplies; previously the phone was connected to any local computer for charging.
In a fit of desperation (and at a suggestion from another contributor on my Telco's forums) I've just swapped the charger to the official Samsung one and the insensitivity problem has vanished, and I'm expecting that the oversensitivity has gone also (I'll have to wait and see as the unit is currently still charging).
The only difference? The official chargers are both rated at 5V 1A, while the Catch of the Day-supplied ones are rated at just 400mA
Clearly the phone sucks harder than 400mA.
…and so does my opinion of the third-party chargers!
(a link to this story will be passed to Catch of the Day for comment)