one way to avoid this 'ghosting' that you are talking about is, immediately after skinning, go and prune small skin weights. (it should be under the skin menu). put the value to .3 or so, and apply. this will remove all the influnces whose value is less then .3 .
also, while painting skin weights, always add values rather than subtract. maya has to keep the total value of weights to 1. so, if you subtract, maya automatically applies the subtracted value to some other random joint. which you don't want.