The fact that you don't want to give money to a charity does not mean you need to find out whether the charity is a fraud or not.

Just an observation of how those most motivated to figure out the effectiveness of a charity are those who don't want to donate. But of course, this only applies to seeking out evidence of non-effectiveness. Charities don't usually think of other charities as competition. Also, most of the time, most just rationalize a reason for non-effectiveness.