Top of Myla's head. Just cat smell.
One of my favorite cats ever was a big, warm, friendly orange tabby. The top of his head smelled spicy! 
Luna smells extremely sweet in a pleasant way, her paws are the sweetest bit.
Sirius does have something odd in his scent. But, he is a bit of a fucked up cat, and acting in a strange mixture of anxiety and extreme attention whoring. His scent does make sense in a sort of way. When we just got him, he downright stank. But, that isn't the case any more.