Anyone who adds a "no?" to the statement. "Good idea, no?" I'm confused. It's either a good idea or it's not.
That's a fairly common usage in Romance languages -- well, Spanish and Italian, at least. I'm not sure about Portuguese, French or Romanian, as I'm not as familiar with them. It tends to be short for "Right?" or "Don't you agree?" When I hear someone use it in English, I tend to assume that one of these languages is their first or second tongue.
It's a cousin of the English usage of using a negative verb when we expect a positive response ("Isn't she lovely?" -- yes, she is). Or tacking a negative verb onto a positive statement to turn it into a question that anticipates a positive response, or vice versa. ("I'm not bothering you, am I?" No, you're not. "You're mad at me, aren't you?" Yes, I am.)
One of my pet peeves is "feel" in place of think, believe or consider. If what comes after can't be described in a single word, it's a thought or belief, not a feeling:
Wrong: I feel he never listens to me.
Right: I feel frustrated because he never listens to me.