Its part of the experience as a bounty hunter. In my case, I have not been paid in half of the bounties I joined especially when I was new and joined any campaigns I find. But now im more particular in joining bounties and look deeply to the project and the team running it.
And probably this will be wortse and worse. Many ICOs have problem to reach soft-cap and they dont have enough money for bounty distribution.
But still you can join signature campaign which is paying in BTC, but they dont offer big rewards.