Flattery
It is interesting that the Orchot Tzaddikim after discussing אמת and שקר, truth and falsehood, continues with a chapter on חניפה, flattery.
This is a more subtle form of Sheker. It may not involve saying anything that is false, but the damage of flattery can be very great.
The main area of damage from flattery comes from condoning bad behavior. It involves being warm and friendly to those who do not deserve such kindness. It can also involve telling others what a good person an evil person might be. If that person shows signs of remorse for their transgressions, the flatterer tells them, that their past transgressions are not so bad.
There is also a negative trait when insincere compliments are given. They are driven by the hope of receiving some future gain for such kindness.
The awareness that this is a really bad trait, is very important. People might justify this by rationalizing and saying that this is the way of the world. It’s not really lying, and it’s easier to give flattery than to give rebuke.
The bottom line is that Sheker is Sheker, and the Torah obligates us to distance ourselves from every type of falsehood. Chanifa is definitely one such form of Sheker.