The devices detect the max charging speed by looking for a resistance between 2 of the pins. iDevices use one resistance to indicate that a high current charge is available, and Samsung use another. However, certain Samsung devices (e.g. the S4) will detect the iDevice resistance and charge at the higher speed.

The reason why some cheaper cables fail to work is that they use a light gauge wire for the voltage pins. The thinner a wire gets, the higher the resistance it creates at a given current, and the more the voltage drops as a result. The device will reduce the amount of current it draws in order to keep the current above a given threshold.

If you don't mind paying through the nose for shipping (e.g. via YouShop), Monoprice.com has some good 28/24AWG charge cables. The thicker 24 gauge wires carry the power, and my phone will happy draw 2A of current over a 6ft cable. If you do order any, make the most of the shipping cost and get a few spares.