「おいおい～、そんなムシのいいこと言うヤツ、面接じゃ会ったことないぜー？まぁなぁ、・・・仕方ないもんなぁ。」
In this case 虫のいい was written as ムシのいい。For context, the character is in a bit of a dire circumstance and is asking one of her relatives for a job, and can only work on specific timing. Thus the relative joking who is supporting her jokingly replied “What a selfish request”.
I have seen katakana being used for emphasis, like word plays or when a character is talking impolitely, I looked up and found that hiragana/katakana can also be used if the kanji can be complicated and used for simplicity. But I don’t really see why 虫のいい was used in katakana here.
2 comments
There’s no way to know for sure, but I think this is often written in katakana because the meaning isn’t “insect”.
So there’s a couple of reasons this can be in katakana, and I can’t tell which because I (unfortunately) just take most of these things at face value.
It could be because ムシ is being used as a euphemism or with a secondary meaning.
Though in this case I think it’s because ムシ is a bug, and animal names, regardless of the simplicity of the kanji are often written in katakana.