Nothing. I just let it and grow itself. Adsense not my main income and i prefer to earn from others method. But i can assure if i concentrate, i will earn well than others.
Yeah, sometimes the same thing happened to me as well. You could get something like 2-3 clicks but that's only worth 0.12 cents I guess that depends on your niche.
Ya thats right that it depends on the niche but direct clicks over the site always yeild me about $0.10 minimum an and at an average of $0.20 per click.
But the adsense for search as compared to it has yeild around $0.o6 here. Whish is bit too less i suppose.