Ugg boots should be seen as an investment; their durability means that they will last you for many years as long as you look after them. There are many products on the market that will clean and protect them, but there are some simple ways of looking after your Ugg boots using only simple household substances.
All you need for a quick regular clean of your boots is a bit of water. Use a stiff brush to knock away any excess dirt first, otherwise you will just push it further into the leather. Then give your boots a gentle scrub with a clean damp cloth. Try not to make them too wet, as this may cause them to stretch or shrink. Afterwards stuff them with rags or newspaper to keep their shape, and leave them to dry in a cool dry place.
These are easily removed with an eraser. You can buy special suede erasers, but an ordinary household eraser should do just as well (do not use a coloured one though—it could mark the boot). Just use the eraser as gently as possible, as if removing a light pencil mark.
Ugg boots are designed to be worn without socks. The wool fleece on the inside helps the air to circulate and the feet to breathe, which keeps bad smells to a minimum. However some smells will build up eventually due to sweat and the buildup of bacteria. This can be treated with a mixture of baking soda and corn starch. Sprinkle two teaspoons of each into each boot, then leave them for a few hours, or overnight if the smell is fairly strong. You can then shake the powder out, and the boots should be back to their normal freshness.
Mix distilled white vinegar with an equal quantity of water, and apply it to the boots with a clean dry cloth to remove any stains. As always, the trick is to work as gently as possible to avoid damaging the leather. For greasy stains, try sprinkling on a little talcum powder and leaving it overnight (you may have to do this several times).
If these tricks do not work, consider investing in a cleaning kit, or taking it to a professional. However you should find that with a little care, your Ugg boots will stay clean and comfortable for many years to come.