I suppose it depends on the domain, like any other parking system. In my experience adsense for domains was a waste of time.
Although, I still see the odd click and revenue from previously parked names with adsense for domains, this is on domains that are no longer using the system. I can only assume that I'm getting clicks from google cache, or waybackmachine. I was unaware that this traffic would be valid, but it's the only explanation I have