expression, noun
petty-minded suspicion; deliberately bad interpretation
Refers to the act of interpreting someone's actions in the worst possible light, driven by a mean-spirited or suspicious mindset. Often used in the phrase 下衆の勘繰りもいいところだ (that's a really nasty way to look at it).
彼が遅刻したのは電車の遅延のせいなのに、上司は下衆の勘繰りでサボりだと思った。
Even though he was late because of a train delay, his boss, with petty-minded suspicion, thought he was slacking off.
そんな下衆の勘繰りはやめて、素直に人の好意を受け取りなよ。
Stop that nasty suspicion and just accept people's kindness for what it is.