I'm making a wedding cake with fondant and might want to use ribbon at the base of each cake. I tried this once but the frosting i used to attach it to the cake came through and did not look so good. Do you use a certain type of ribbon? what do you use to attach it?
Use a thicker grosgrain ribbon and attach it with a few tiny dots of royal icing. It's a matte/woven ribbon and less easily stained by condensation/icing than something like satin, for example.
You can also ask your local florist to buy a few yards of the special waterproof florist ribbon they use on bouquets. It comes in many colours and it's really water/stain resistant too.