I always read the whitepapers before investing in ico or joining bounty campaigns. This is the first thing I do for understand project main idea and solutions.
There is where the information for the project is located. Whitepaper is a plan for a project and you can read whether it will become successful in the future. You can read there mission and vision of the team why they are developing such project as well as the allocation of funds. You can know there if the project is legit and truly going to develop well and the contributors can earn for the future.