It may smell like all kinds of things but salty-creamy-musky within a smoother version of isopropyl alcohol seems to describe it pretty well. Dominique Dubrana calls it “humid, earthy, fecal, marine, algoid, tobacco-like, sandalwood-like, sweet, animal, musky and radiant.”
It’s unlikely that many major perfume companies have used real ambergris in the last thirty years when you're talking about using it in the quantities that it takes to make a regular fragrance to be sold in any quantity at all. Many perfumers, even many of the best best ones, will tell you they’ve never even smelled real ambergris in its most smelly form. From what I understand, Creed uses a combination of synthetic ambergris (Ambroxan - Firmenich, 1950)) and sandalwood (now also synthetic), and has for a long time.
One prominent perfumer recently said that Muscs Koublai Khan resembles the smell/feel of ambergris that he knows best.
As far as I know, all of these are regularly used, often in combinations with other things, as substitutes for real ambergris: Dihydro ambrinol, Ambroxan, Ambreine, Timberal, Grisalva, Karanal, Cetalox, and a wide variety of synthetic Sandalwood bases - Santaliff, Javanol, Polysantol, Firsantol, Ebanol, and a ton of others. I’m sure there are a lot of new ones as so many new synthetic aroma chemicals are coming out all the time from Firmenich, Symrise, IFF, Givaudan, and so many others.
I smell a large number of fragrances that could easily fit the basic idea of "ambergris".