Party is really a gateway poker room, so if you’re on a CPA and can recruit a ton of new players, it can do very well for you. And these players can turn out to be whales in the long run, but it can take months for that to happen.
When I was doing well in the SERPs for some basic online poker review terms, I was getting a lot of Party Poker signups. But they would rarely play for real money, and so I was not getting much revenue unless I was doing the CPA.