That's what I thought. Of course she probably has a partial knowledge of In Hun as someone who took care of Nakyum. She is biased by her first impressions.
Yes, clearly it's only a very shallow impression and premature judgment. Inhun's a professional liar, but you'd have to be a bad judge of character or just not paying much attention to miss what a condescending, egotistical creep he is. The kisangs hired Inhun yet Nakyum doesn't even know how to read and in an early chapter Inhun admitted to Seungho that he doesn't like teaching and doesn't bother to properly educate his students since they're the children of "ignorant folk" and "destined" to be farmers. As immoral as Seungho is, even he gave pause to that lol
I like Heena but she's not the best judge of character if she believes Inhun is any better than those nobles.