I can understand why you are enraged. I agree that the signages are an eyesore.
But if I were the seller, I would be very happy if the signages help sell the house faster.
The agents are simply doing their job. Instead of pointing fingers, perhaps we could choose to focus on the positive side of it.
For example, we can look at it this way: by promoting the house heavily, the agent is able to sell the house quickly. Therefore, there would not be many "inventory" in this neighborhood. And when supply is low, the price spike! It's a good thing to all residence, isn't it?
Faster movement of inventory also bring the perception that the area is very popular, and that's a very good thing as popularity and perceived value is correlated.
While I agree the agents could do a better job with the signage, I don't have too much problem with them trying to promote the house heavily. In fact, I wish them success, the more successful they are, the better it is for us.