In the United States, smell copyright is well-established case law. Smells can be copyrighted if they're not a functional part of the product. Perfume no, smell added to shovels to distinguish your brand, sure.
That's interesting, I thought the smell was a result of the ingredients - which would make it non-distinctive and unsuitable for a trademark (as others would be excluded from making the product so the trademark would operate as a perpetual patent).
Maybe the smell is a trademark only for other goods (I don't know what Class Playdoh falls in, toys?), eg Playdoh scented merch?
I think one of the problems is that color and what you see is somewhat tightly related where taste and how taste works is highly varied.
While you can get some sort of single-molecule chemical representation of some specific smell or taste, that would be static (as in, the formula or construction wouldn't change) but most people would smell different things.
I suppose for those 'inventions' the recipe or method would be trademarked/copyrighted/patented but not the result.
There is a whole world of professional "noses" used by perfume companies. They have a system for describing "notes" but I know far too little (and honestly, don't want to know more) to say more than that.
The same for wine. However, research has shown that adding red food coloring to white wine, causes people to smell the notes that are usually smelled in red wine. [0]
I’m not a trademark lawyer, but I used to work with them in the UK. From what I recall, trademarks need to described in language accessible to ‘everyman’ to be protectable. So when I was there, about 5 years ago, I don’t recall that there had been a successful bid to trademark a smell because a gas chromatograph didn’t fit the bill.
