In this classic (but evergreen) post from his Cause Marketing blog Selfish Giving, Joe Waters makes some great points about what makes for a great cause marketing campaign. He compares a disastrous campaign by KFC with a much more effective one led by White Castle, and points out why the latter succeeds where the former fails. His ultimate point is quite simple:
Fast food restaurants can and should be involved with causes. It's all about fit and execution.
In other words, a good campaign requires a logical fit between the product and the cause, and ought to be scaled appropriately for the circumstances at hand. Very good advice.