Hi Dina,
I find that you will have lighter and darker patches in the naked ganache finish when you are still working the ganache as it is starting to firm up and set. I normally ganache my cake as usual (either using the lid method or upside down method……Check out Betty from Glasshouse Cakes for a great tutorial https://www.facebook.com/pages/Glasshouse-Cakes-and-Supplies/187704901264619#!/photo.php?v=10200869801279702&set=vb.187704901264619&type=2&theater) and then once the cake has set and has sharp edges, i apply a very thin layer of warm, runny ganache and quickly smooth it over before it starts to set. It should stay dark and have a shine if you don’t touch it once it is applied.
Hope this helps,
Louisa
