Not just antis or trolls. Also other k-pop fans do this, picking only the 1-2 ugliest teen pics of an idol as supposed evidence that an idol had done PS.
This never made sense to me. I know there's a few pics when I was like 14 years old when I didn't care much (yet) about make up and styling where I look 'ugly' (I was late in blossoming up) that are a world of difference compared with pics a few years later where I look my best where I'm all styled up, make up in place, dressed to kill and out to party. There's huge difference in visuals between those ugly pics and best pics and I'm sure everyone has that sorta pics - best looks vs 'ugly' ones.
It would make far more sense to pick the visually best teen pics of an idol - because then you know what their best looks could be as a kid and then compare with their later looks.
Or at the least pick ugly and best teen pics of an idol to have a better overview and then compare with their pics after they became trainee or debuted.
Picking only 1 or 2 ugliest teen pics of an idol while ignoring their better looking teen pics to 'prove' PS feels like cheating.