I have the whole ass list for that but in general I dislike those Kpop Idols turned actors/actresses....Don't come @me ..Just because they acted ( It is rather blank stares , smile, laughs, cries )in few  of their MVs for split seconds.. they think they are actor now...leave that job for actors/actresses...Many deserving actors and actresses have to manage being supporting cast  just because some Idols thought "acting is their cup of Tea". Their dumb fan hypes them and bring ratings which in turn makes dramamakers  to bring them more....

baek in Scarlet Heart acted pretty decent ;-; 

Besides, this is market, and names are brands, known brands, sell more, that's the way world works

Gong Seung Yeon.
I dislike her way of acting, and also  her roles make me like her even less

Kim Hye Ok.

I can't stand when she starts her high pitch screaming and dramatics...I either have to skip the scene or put it on mute. Sometimes I'll completely skip a drama that looks pretty good because she is in it. Damn Banshee! 

Hate is strong word but I dislike Shin SeKyung

I dislike Lee Jong Suk's acting.. He's playing same characters all the time, same mimic, same way of speaking, same mannerism. In my opinion he's overrated and one of the worst trending actors in Korea right now. I think his best performance was in movie V.I.P because it was totally out of box for him. I hope he gets more roles like that and then maybe I'll change my mind (like it happened to me in case of  Yoo Ah In's acting).

I've always hated Suzy's acting and I don't understand why they keep pairing her with actual talented actors cause she end up dragging them down with her. I used to not like park Hae Jin for literally no reason but after Cheese And The Trap he grew on me.