Participating into bounties or twitter campaigns is really a good way on earning altcoins and even bitcoins, but you have to make some researching about the ICO project you want to participate in and know all the high reputable bounty managers that will surely pay you, to avoid of wasting so much time and efforts to those campaigns that are not paying.
Joining on twitter campaign or other social media campaign doesnt really requires a reseach and also the manager that manages it doesnt really matter if it is well known or reputable. all does matter is if the funds allocated for that campaign is already been escrowed by the manager or not. if yes , then that is probably legit and will surely pay you as long as youv done the given task succesfully. If not then that could be risky.
you should also check the pay rates before you apply because you might get dissapointed at the end of the campaign if you just join and join without actually reading the rates and rules as well.