insincere

1. ADJ If you say that someone is insincere, you are being critical of them because they say things they do not really mean, usually pleasant, admiring, or encouraging things. 不诚恳的; 虚伪的[表不满]

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。