Toy giant Hasbro is trying to trademark the smell of Play-Doh
Andrei Mincov's commentary on the original article
Scents can be trademarked in some jurisdictions but they are considered to be unconventional trademarks. The biggest problem with trademarking scents is being able to properly describe the scent to distinguish it from other smells. Sending the package to USPTO is usually not enough because trademark registration is not done for the sake of the Trademarks Office. The registration should be able to give the public sufficient information as to what they are allowed and what they are not allowed to do with a particular brand. And if it is impossible for the public to know what is protected without having to go out and buy the package from the trademark owner, it would usually not proceed to registration.