If the switch harness is properly connected and not damaged, the charger is disconnected when the receiver is turned on. You should see the charging indicator go off on your wall-wart charger. The transmitter also disconnects from it's charger when turned on. One of the reasons for this is to keep the slightly elevated charging voltages from reaching the electronics of the radios and causing possible damage. Aftermarket fast chargers may cause even more damage without this protection.

Since you are not going to fly with the charger attached, I would not worry about the flutter unless you see it with the charger removed

Make sure your switch harness is properly installed. The switch should still turn the radio on/off even if the charger is plugged in. If not, something is wrong