Every "good guy" I've ever met that said these things rejected their shadow selves and at least subconsciously believed that it couldn't be detected if they hid it. I learned from my own personal growth journey and detachment from a very strict religion that was keeping me fragmented that we don't hide it as well as we believe. With men, I found that it manifests as aggression that then sorta leaks out in their day to day lives the longer they supress it and then it turns into aggression-like behaviours like negging, cynicism, cruelty, lack of consideration for his woman's feelings, etc. The more they supress, the worse it gets.

That's what gets detected by women who inevitably leave them because they aren't as "nice" as the front they put on (which is a huge reason why I don't hide mine, rather be loved for who I am yadda yadda). I think a bigger problem is that they often don't know how to become better or that they even should, why it's vital to live a healthier mind, helps us face demons that aren't even ours (when we 'good guys' get turned into a projectionist's scapegoat, which may lead to unfair punishment, which leads to the cliché 'nice guy' rage), it can help us tap into a deeper power once we learn to utilize it right, etc.