As a middle-aged American, I’ve never heard or used the phrase either. But A google books ngram for a similar phrase “you’re a caution,” shows it making a resurgence. https://books.google.com/ngrams/graph?smoothing=3&corpus=26&year_end=2019&year_start=1800&content=You+are+a+caution&direct_url=t1%3B%2CYou%20are%20a%20caution%3B%2Cc0 It still doesn’t seem to be a widely used phrase, but maybe we’ll be hearing more of it.

As an American, although I've used the adjective, "smart," before to refer to a person's style of dress, I've used it as a Britishism. To answer Su.Ki.'s question: I imagine that most of the other adjectives we use would be shared among English speakers. For a man, the adjective "sharp" comes to mind. ZZ Top put their American spin on it here: https://www.youtube.com/watch?v=7wRHBLwpASw. For inanimate things like offices and cars, "sleek" is a good word. Lately, I'll hear the slang, "bougie" for both people and things. This is more of a pejorative word, when you want to give a subtle dig to whatever you are describing.

For another perspective from the United States: The American Heritage Dictionary lists "bit" as a possible past participle, in addition to bitten, with no usage note that such use is non-standard. A "bit" about The American Heritage Dictionary: Its stance on a number of grammatical issues can be, admittedly, liberal sometimes. But, its usage panel is a list of who's who of Americans working in the fields of linguistics, literature, criticism, etc. Generally, it will include a "usage note" if a word is considered non-standard or if there is a debate about a usage. These notes are wonderful, as well as are the pictures in the hardcover version (the online version still has the usage notes). The dictionary is actually great reading. Highly recommended!