The Ethics and Morality of Spellcasting

How is one to define what is an ethical spell? We are all familiar with the Threefold Law and variations thereof, but how can we guarantee that the Gods are at our standpoint when we judge our spellcrafting to be within the bounds of the Wiccan Rede? True, not all those who cast spells are Wiccan, but most feel that they have the responsibility to "Harm None".
We can start from the popular request; "come to me" love spells. Generally these are seen across the board as interfering with another's free will and can bring disastrous results in the shape of the wrong lover, or the lover who will not stop loving. With these potential drawbacks in mind, why are so many people still willing to run the gauntlet in order to find love? Is our allegiance to our happy family ideals stronger than our allegiance to our fundamental ethical code?
When the outcome is somewhat darker, can we still justify the working of a spell? Hexing a competitive work colleague to ensure a raise is a work of bitchcraft; but if we are doing it to get the money to support our own does that make it acceptable? However, if the colleague dies as a result of our work, is it our fault? Or would we simply shift the blame onto the Gods for allowing our intention to become so magnified? As spellcasters do we not have a moral copyright over the outcomes of our spell, since it is our intentions in practice?
However it is possible that death was in the original equation of the spell. By denying others the right to live, we are extending beyond the factor of their will and into the realms of playing deity. As Pagans we recognise the deity within ourselves, but if we construed that to mean that we have the powers of the Gods and as such the right to decide who should live or die, the word Pagan would become synonymous with Dictator and our planet would be a very lonely place. But if one cannot ethically take another human's life, where does our compassion end? Livestock that will provide food? What we consider to be vermin? Insects and other creatures discounted from the spiritual spectrum merely by size?
We must consider however, that death is not always inflicted as punishment. How does our moral code apply if we wish to give death as a gift to end suffering? Are we still punishable by the Threefold Law, or do our good intentions negate us from karmic retribution? We may justify our behaviour to ourselves, but our true intentions will always show in our spell. That is, granting respite to one in suffering with whom we have fought and become angry may not always leave us with the "morally clean slate" that we would wish to believe in. If we believe in the wisdom and power of the Lord and Lady, is it not insulting to their judgement to work any spells? Or are we simply exercising our own Gods-force in a petition to their power?