Casting revenge curses that work

Ahhh yes, the exciting and usually controversial topic of revenge spells! Are they ethical? Are they part in the darkest black magic and should in no way be used? As stated in most Wiccan redes, will they invoke the returning power from the 3 x 3 - meaning that all spells put out into the universe will come back towards the spell caster 3 instances as strong? The answer is YES and NO!