I use my same basic recipe (which contains Castor oil) but the scent is a blend of 5 EO's
Cedarwood, Peppermint, Rosemary, Lavender, and Geranium Rose. I use them them in equal amounts. There it is, I just gave away my secret! oh well
I always get asked if there is citronella, lemongrass, or catnip in the soap, and there could have been, but I don't prefer the smell of citronella -it makes me think of OFF! and those candles that are awful!
I make two varieties: one with ground oatmeal and one without. But since I rarely have them both in stock at the same time, I can't tell you which sells better. Some people say that their dogs are allergic to oats (which I guess is in a lot of dog shampoos).
I also use this soap when I go camping, and I market the soap as "bug repelling soap for dogs and their humans" so its clear it can be shared among the whole family!
My dog smells so nice (pretty, even) after his bath, and his fur is super soft for at least a week. He does tend to rub himself on the back of the couch and the carpet, but I think it's just because he is wet, not that he dislikes the smell.
have fun developing your brand!