Probably yellow. Especially when it comes to clothes because I've never found a yellow alone fabric that looks nice on me. It's an okay colour outside of fashion and furniture/interior, in my opinion.
I don't like any versions of green, cause green is just too common, too mainstream. There is too much of it in this world that it just is dull to see something green after awhile. Overall it's just a boring color to me, I wish grass was a different color than green that would be awesomeee
It depends really on what abject has that colour. All colours will look bad on something. There's that shade of Green I don't really like to see on shiny Pokemon, namely Espeon. I also don't like seeing bright pink cars.