If they are worth it to kill, really depends on your goals with your account and your current situation. I, personally, do not think they are worth it. If you are at the level that you can kill brutal blue dragons at a fast pace, you are better off doing the dragon slayer two quest and try your hand at Vorkath. A brutal blue dragon kill is worth about 10k on average. They are pretty hard to kill and deal quite some damage, so I would not recommend you going here if you want to make a lot of money. After your supply costs, and considering you are not going to be able to pick up every drop you get there, the money will be around 6K in net profit. This is assuming you use melee. If you are using range, then your profit is going to be a bit lower due to the fact you are losing bolts, darts for zulrah scales. You are looking at a profit of about 300k an hour with very slow Exp. You should check out Vorkath in that case, the money will be much higher an hour, and it is more fun to do.