I'm not sure that bounty campagin can be passive income, you are really working for those tokens and you also can't be sure you will recive good reward for it. Probably it's waste of time.
In the unpredictable world of bounty campaign, different opinions may be formed but what is more important is that before joining the campaign you should be aware of its background or check reviews if it is legit and if it's back up by strong developers, team or campaign manager. If you fall into good campaign then it can absolutely provide better results and earnings, otherwise that's what you call waste of time, because you lack strategies, however don't be discouraged instead learn from the experience to be a better person than yesterday.