Filtering the truth about whales – Should environmental organizations fight fire with fire?

Despite cries over the unsustainability of Icelandic whales the science simply tells us that this is not true. The statistics show that there is an abundance of whales around Iceland and it would take far more that the issued quota to have a dangerous effect on the whale population in the region.
Through the years NGO’s have cried foul over companies and governments using their PR practioners to spin or filter the truth, and rightly so. Many practices have not only been unethical but illegal. But does this justify fighting fire with fire?
A reputation is the most diffucult thing to build, just ask a PR practitioner. It can take a lifetime to build and a second to destroy. There are indeed several reasons against Icelandic whaling such as humanitarian and even economical. But the reasons need to be clear, are they emotional fears or rational ones? In a recent South Park episode this topic was explored. As scenes of Japanese killing whales disgusted people, the boys of South Park tricked the Japanese into killing cows and chickens instead. The final scene shows the Japanese running around killing cows and chicken with one of the characters saying “finally, they are normal like us”.
Trying to relate to emotional fears simply stating false claims does in some cases gather the support they need, but is it good in the long run? There are a lot of issues that organizations such as Greenpeace do that are worth fighting for, to they want to sacrifice their credibility on this one?