I have suspect that you don't lose resource points and you don't get gold you you kill some soldiers..I started an attack and I won it but I lost about 14,000 soldiers but it seems my general score is the same and also his score looks like being the same. Besides I killed a lot of elite soldiers plus resources in the fortress..but I got just 800,000 of gold. It seems to be very few.
Anyway I didn't check exactly before the attack..just I remember he has about 600,000 of gold in the fortess when I spied him. So, as i wrote before, it's just a suspect. Next time I'll pay more attention on it