rule of thumb is to use oxidizer on organic stains and reducer on synthetic stain. Problem is often you have a little of both in wine or coffee. Some wineries may add artificial dye to achieve a certain in their product. With coffee, it's often decaffeinated coffee that's the hardest to remove. Some decaffeination processes take a lot of the original color out of the coffee so they replace it with dye. Although it seems counter intuitive to use a reducer on an organic wine stain, personally, I find it the safer route to start with, then if I haven't removed all of it, my last step, after rinsing thoroughly, is to use a slow acting oxidizer like a 2 part peroxide/ammonia solution. Reducer works by taking away oxygen, oxidizer works by adding oxygen. We have had coffee stain reducing agents for years and if used properly, they work well. That's all we used until they came out with the 2 part peroxide stain removers. You have to have patience. They don't always work immediately.