If you focus on good projects there is a number of ways to really make a good success with a bounty. If you have a high bitcointalk rank the signature might be worthwhile. You can always go for translation bounties if you have an additional language to English. Also I have seen a lot of people very successful with Twitter bounties, if they have a following over there.
The higher the level, the more you get. But if you encounter a dishonest project and don't give the money at the end, then it is a big loss. A person's energy is limited, he can only participate in very few activities, and there are very few people who need to do translation. The key is how to find good projects and avoid junk, because too many bounty is very good at first, but it is very rotten.