I've never come across a scented A. obesum, good or bad, just no scent at all, but there might be some fragrant varieties. I really don't know.

I have never smelled one that had much fragrance. And from what I've read, the most fragrant ones are only mildly fragrant.

Fragrant Adeniums can be grown to have more than a mild perfume. Terpenoids are a class of organic chemicals that play a major role in plant fragrance. Carbohydrate rich feeding can help boost terpenoid production, especially with molasses. Kelp and properly made compost tea are also great for boosting fragrance.

Here is a link that might be useful: Pics of some of the Adeniums!