“You genius” sounds like a compliment to me. A “funny” compliment. Would it be taken as sarcasm in the US? It really depends the tone I guess but in Australian english I wouldnt interpret it as sarcasm.
I think that changing it to something gramatically correct would make it into a compliment. “You are a genius” would make it positively charged. However, I would expect “you genius” to be something that, for instance, someone would exclaim when someone cuts their hand when trying to open an avocado. Meanwhile I think it would be strange to exclaim “you genius” when someone solves a partial differential equation. But it probably does rely on the tone.
“You […]” makes pretty much anything an insult.
A positive word implies sarcasm. “You genius”. “You hero”.
A random noun drags out the negative aspect of the noun or implies lack of a brain. “You french fry”. “You paper bag”.
Adding a random adjective just strengthens the statement. “You british bathroom sink”. “You beautiful parking lot”.
Of couse it depends on delivery, and using random words makes some strange insults, but I rarely see “you […]” turn into a positive compliment.
“You genius” sounds like a compliment to me. A “funny” compliment. Would it be taken as sarcasm in the US? It really depends the tone I guess but in Australian english I wouldnt interpret it as sarcasm.
I think that changing it to something gramatically correct would make it into a compliment. “You are a genius” would make it positively charged. However, I would expect “you genius” to be something that, for instance, someone would exclaim when someone cuts their hand when trying to open an avocado. Meanwhile I think it would be strange to exclaim “you genius” when someone solves a partial differential equation. But it probably does rely on the tone.
I’ll take “beautiful parking lot” as a compliment and there is nothing you can do about it