Maybe a better statement would be, "If you donate to the Red Cross then know what your donation is going to support..." Then maybe you can enumerate the complaints and, if wanted, provide citations.

As it is, I think some folks may take offense with you telling them how to spend their money. I, for one, read it as you trying to tell me what I can or cannot do.

Edited to add: I see your dead reply. The difference between my suggestions and your post is that you demand, as opposed to ask. You may notice that I'm making a point of not saying you should do something, but that pointing out that you can choose to do something.

It's received much more gracefully and people are much more open to the ideas when they are asked, instead of when they are instructed. But, it's entirely up to you how you take it and what you decide to do with it.

I've spent years learning to say could instead of should. It has helped me immensely.