In a pinch Dawn dishwashing liquid in water will cut grease more effectively than many other grease cutters. The suds helps the process. Not a green product but a good resource of last resort.
Bartender's Friend is a uniquely adaptable cleanser that cleans many surfaces and kinds of dirt. One of its uses is removing stains--on porcelain, countertops, etc. I've found nothing else that works so well at this. It's got one ingredient that's made in a laboratory so I don't use it as part of my standard toolkit. But, in a pinch, it's a handy product to have around.
I use ecofriendly products as much as I can, probably about 95% of the time. But there are moments when you need something to blast through a super build up of dirt that goes a step beyond. This is the first in a series on products to use in a pinch when nothing else will work.
Bathroom showers and tubs can built up soap scum that is really hard to get clean. When even my best bathroom product, Ecover Bathroom Cleaner, won't do the job, I turn to Zep Bathroom Cleaner. It's the most potent soap scum remover I've found!
Here is a product I used to great effect. Unnecessary backstory: I tried an experiment of keeping my loud new cat in the basement during the night and my new cat experimented with clawing the wood basement door, trying to get out. Mineral Bee Wood Conditioner, a food grade mineral oil made with beeswax, covered up the scratches beautifully. I'm looking for other uses too. The cat, by the way, won. No more basement. Ear plugs are doing the trick.