Hi Karen: Here are a few suggestions:
Here are some sites that have specific cleaning solutions:
For Grease: https://www.hunker.com/13423524/how-do-i-clean-a-grease-stain-out-of-my-uggs
For Salt: http://www.howtocleanstuff.net/how-to-clean-white-salt-marks-from-ugg-suede-boots/
Just about anything: https://cleanmyspace.com/the-ultimate-ugg-boot-cleaning-guide/
Hello. I purchased a fabulous wool washing soap solution when I purchased my boots that were from New Zealand. It works very well.
You may wish to contact Ugg directly for the best solution for their product.
Here is a solution from one of our Hometalkers
Here are some cleaning ideas for you : https://www.ugg.com/care-and-cleaning-instructions.html
I have black ones, and I am always getting salt stains on them. All you need is a damp microfiber cloth and a little patience to remove them.
Here's a good tutorial: https://www.youtube.com/watch?v=UFVlQ3ee3_Q
I think this can help you:
Many dry cleaners clean UGG boots.