Madame Pernelle: "And you, his sister, seem so pure, So shy, so innocent, and so demure. But you know what they say about still waters. I pity parents with secretive daughters." (1.1.11)
Madame Pernelle accuses her own granddaughter of being a liar and, perhaps some other less savory things. She presumes that she is guilty of something even though she clearly has no evidence.
Damis: "Ah no, Grandmother, I could never take To such a rascal, even for my father's sake. That's how I feel, and I shall not dissemble. His every action makes me seethe and tremble With helpless anger, and I have no doubt That he and I will shortly have it out." (1.1.21)
Damis is firmly opposed to any kind of deceit. We see later on that his commitment to telling the truth causes a lot of trouble.
Dorine: "Oh, yes, she's strict, devout, and has no taint Of worldliness; in short, she seems a saint. But it was time which taught her that disguise; She's thus because she can't be otherwise. So long as her attractions could enthrall, She flounced and flirted and enjoyed it all, But now that they're no longer what they were She quits the world which fast is quitting her, And wears a veil of virtue to conceal Her bankrupt beauty and her lost appeal." (1.1.33)
Here, virtue is worn as a kind of make-up, to cover over the signs of aging. It is a mask, a way of deceiving those who might have found some cause for criticism.
Dorine (To Mariane): "Your father's addled; he's acting like a dunce. Therefore you'd better humor the old fossil. Pretend to yield to him, be sweet and docile, And then postpone, as often as necessary, The day on which you have agreed to marry." (2.4.90)
Dorine advocates lying to Orgon; as long as she's using deception to do good, she has no qualms.
Elmire: "Some women might do otherwise, perhaps, But I shall be discreet about your lapse; I'll tell my husband nothing of what's occurred If, in return, you'll give your solemn word To advocate as forcefully as you can The marriage of Valère and Mariane," (3.3.32)
Elmire, like Dorine, is OK with deception if it serves a good purpose.
Damis: "She, with her too gentle disposition, Would not have told you of his proposition; But I shall not make terms with brazen lechery, And feel that not to tell you would be treachery." (3.5.1)
Damis, on the other hand, is unwilling to compromise his morals. As a result, he's disinherited and more trouble is brought upon the house of Orgon.
Elmire: "You've been too long deceived, And I'm quite tired of being disbelieved. Come now: let's put my statements to the test, And you shall see the truth made manifest." (4.3.22)
Elmire's decision to step in and show Orgon the truth is based on both her compassion for Orgon and her overall fatigue. She wants to save him and save herself the trouble of dealing with him any longer.
Elmire: "I'm going to act quite strangely, now, and you Must not be shocked at anything I do. Whatever I may say, you must excuse As part of that deceit I'm forced to use." (4.4.7)
Elmire only uses deceit as a last resort, in order to save Orgon once and for all. She makes it very clear that she's "forced" to use it, and is up front about it being deceitful. She's no hypocrite, after all.
Tartuffe: "To please you is my joy, my only goal; Your love is the restorer of my soul; And yet I must beg leave, now, to confess Some lingering doubts as to my happiness. Might this not be a trick? Might not the catch Be that you with me to break off the match With Mariane, and so have feigned to love me?" (4.5.5)
Tartuffe, world-class liar that he is, knows a trick when he sees one, but he's eventually overcome by his lust.
Officer (To Orgon): "Sir, all is well; rest easy, and be grateful. We serve a Prince to whom all sham is hateful, A Prince who sees into our inmost hearts, And can't be fooled by any trickster's arts." (5.7.19)
The King/Prince is something like the anti-Orgon. He knows a liar the moment he sees one.