Idols have "images" that are picked for them by their staff. What we see from them isn't even 10% of their true selves. A lot of "shy and sweet" girl personas may not even be close to true like Lesserafim's Garam and Soojin's off-stage personality. A lot of potential "scandals" remain unsaid because agencies have too much power to hide dirty things. Obv, I am not saying they are all bad people. Majority of people are nice, but fans could never tell by what they see on camera, that's the point.
Then again, if I find out some of idols that I like aren't conventionally nice people I don't think I will care that much. Disappointed a little, maybe, but the main point was always me listening to their music and them being bad people won't stop me from listening to a song I like.