Crowdsourcing pitfalls

Your crowdsourcing effort will most likely fail if…

your crowd is not diverse.
your crowd all thinks alike.
their task is not clear.
their mission is not compelling.
the technical platform is poorly designed or overly complicated.
there are not continued areas for growth and engagement over time.
the interface and the organizers are not responsive to change.
the community lacks social moderation or healthy behavioral norms.
it lacks mechanisms to address technical abuse and human harassment.
you do not recognize or empower the core users of your platform.
you lock it down and people have to jump through hoops to participate.
potential users lack free time, skills, access or awareness to contribute.
volunteers are hampered by legal restrictions or monetization attempts.
another more interesting or better crafted opportunity comes along.
you never attract enough people to have a crowd in the first place.

Source: Wikimedia blog