I've heard many say that flower scent is perceived differently by different individuals and I guess it's true because although I've heard many say that Hoya carnosa blooms smell like chocolate, I never detected much fragrance at all on any of my carnosa plants. I used to grow the beautiful Orchid Cactus Epiphyllum oxypetalum too, which is said to be highly fragrant and yet I could never detect that amazing perfume! I do have a very sensitive sense of smell with some plants and Hoya australis is one of my favorites for it's wonderful fragrance; one bloom will perfume an entire room! Years ago, I had a few baskets of
Wax Plant (Hoya lacunosa) and brought them all indoors one winter when we were expected to have a freeze ... the fragrance was amazing but very overpowering and I ended up having to move the plants back to the porch!
Just remember, due to the fact that they attract nighttime pollinators like moths and other insects, Hoya fragrance is usually highest after dark ... so when your plant blooms, the fragrance should be most noticeable at night.