You said I'm incorrect, but then gave zero evidence that a charger that uses a USB cable to charge will give out a dangerous voltage and could cause the phone to overheat. What I said is a fact.
Here's a link to the USB 2.0 specification:
USB.org - USB 2.0 Documents
Check out section 7.2.2 of the "usb_20.pdf" file.
If a charger is outside that range it can not legally display the USB symbol. So how can I be wrong that a legal device with the USB symbol (which the Samsung chargers are) have a voltage outside that range like Kayla Smith3 said? If the Samsung chargers comply with this then the phones can't require a voltage outside that range, so any charger with the USB symbol will either supply a valid voltage or be subject to litigation from the USB-IF for using their symbol but not complying with their requirements.
Your phone charging too slow has nothing to do with the voltage the charger puts out. Chargers can have too low of a current capability (like a PC) or not have the correct scheme on the data pins (e.g. they left the data pins floating) to indicate that it's a charger and give too little current, but that has absolutely nothing to do with the claim that Kayla Smith3 (who, based on the name an avatar is probably not a he) made.
I'm not sure how a charger could possible cause B to happen. All a charger is is a 5V source with some current supply capability that has probably either shorted together or put some pull resistors on the data pins. The phone takes that 5V, converts it to 4.2V and manages the charging based on the voltage at the battery and the temperature. Unless the charger is broken or non compliant the charger can't draw current and the phone won't just randomly go into some state where it draws a ton of current for no reason because of the charger.
My understanding is that some Samsung phones apparently check to see if the shield on the USB cable is attached to signal ground and will make a determination of how fast to charge based on that, but that's a current draw issue and has nothing to do with the voltage and won't cause the phone to draw extra current.
So, how exactly am I wrong and what is it that Kayla Smith3 that was correct?