So it appears that the last wave is the only one that could potentially have any resources leftover without stolen goods. Or at least that is what I take away from this.
What happens is if you raid the Camp, the troops that you don't kill and the resources you didn't stole are added to the next wave of the camp. Which usually has less stolen goods. So this increases your losses and except for early game you can more often than not clear all the resources but not all the troops in the wave you raid. Therefore allowing only to Attack is a better option.
But this is my opinion, lets see what everyone thinks about it