Recently i took part in couple of bounty campaigns,and i though i can earn some decent amount through it...but it was a total waste...i took part in targetcoin and coss ico campaign and after 2-3 months i recieved the bounty which is worth only about 8 USD including both

it was just total waste of effort and time
It really depends on the budget of the project.
No, the most important thing is, it's depends from the project, is it still active after ICO ended? And will the dev keep their promise to always update any result with their road map.
If dev is honest and not plan to change the rules of bounty payment then the campaign is good, And it is our obligation upon selecting on which one is the best campaign to participate it since if the campaign is nice then we will be lucky since we can possibly earn huge from it. And joining on the altcoin bounty campaign is gamble since we doesn't know on what is the faith come to the project we join.