You have to watch out for insincere people.

你得小心那些虚情假意的人。

youdao

Some people are so terribly insincere you can never tell if they are telling the truth.

有些人虚伪得可怕，你绝对无法搞清楚他们是否在讲真话。

《柯林斯英汉双解大词典》

All too often such policies are an insincere form of virtue signaling that benefits only the most privileged and does little to help average people.

这些政策往往是一种虚假的美德信号，其只会让最有特权的人受益，而对普通人几乎没有帮助。

youdao

"If you're filming in London people are so often insincere because they are taken over by the crews, " he said.

BBC: Newsbeat - Entertainment - Jamie Oliver defends new series

The people feel they have been betrayed all these years by insincere leaders.

CNN: IS ESTRADA UNSTOPPABLE?