I would NOT use "sumptuous" in relation to smells. Recommended usage:
--------- sumptuous
1 a : involving large outlay or expense : COSTLY, LAVISH <the sumptuous dinner given by a railroad king -- Julian Maclaren-Ross> <a sumptuous piece of bookmaking -- Lionel Stevenson> <a sumptuous education -- O.S.J.Gogarty> <general effect is one of an ov
Perhaps because of the "luxurious" meaning, or perhaps because it sounds like "scrumptuous," but either way, I don't find anything odd about it. I would expect a sumptuous smell to be rich, potent, and very good.