The two clauses describe two phases of the mutual affinities of evil. The evil-doer delights in lies, the liar in bad words.

A wicked doer giveth heed - An evil heart is disposed and ever ready to receive evil; and liars delight in lies.

A wicked doer giveth heed to false lips,.... A man of an ill spirit, of a mischievous disposition, that delights in doing wickedness; he carefully attends to such as speak falsehood; he listens to lies and calumnies, loves to hear ill reports of persons, and takes pleasure in spreading them to the hurt of their characters; and men of bad hearts and lives give heed to seducing spirits, to false teachers, to inch as speak lies in hypocrisy, who sooth and harden them in their wickedness;
and a liar giveth ear to a naughty tongue: or, "to a tongue of destruction" (a); a culumniating, backbiting tongue, which destroys the good name and reputation of men; and he that is given to lying is made up of lying, or is a lie itself, as the word signifies; who roves and makes a lie, as antichrist and his followers; such an one hearkens diligently to everything that may detract from the character of those especially he bears an ill will to: or it may be better rendered, "he that hearkens to a lie gives heed to a naughty tongue" (b); for a lying tongue is a naughty one, evil in itself, pernicious in its effects and consequences.
(a) "perniciosae linguae", Tigurine version; "linguae confractionum calamitatum, injuriarum", Vatablus; "ad linguam exiliorum", Michaelis. (b) So Michaelis.

Flatterers, especially false teachers, are welcome to those that live in sin.

Wicked doers and speakers alike delight in calumny.

4 A profligate person giveth heed to perverse lips;
Falsehood listeneth to a destructive tongue.
The meaning, at all events, is, that whoever gives ear with delight to words which are morally reprobate, and aimed at the destruction of neighbours, thereby characterizes himself as a profligate. Though מרע is probably not pred. but subj., yet so that what follows does not describe the מרע (the profligate hearkens...), but stamps him who does this as a מרע (a profligate, or, as we say: only a profligate...). מרע, for מרע, is warranted by Isaiah 9:16, where מרע (not מרע ton, according to which the Venet. here translates ἀπὸ κακοῦ) is testified to not only by correct codd. and editions, but also by the Masora (cf. Michlol 116b). הקשׁיב (from קשׁב, R. קש, to stiffen, or, as we say, to prick, viz., the ear) is generally united with ל or אל, but, as here and at Proverbs 29:12; Jeremiah 6:19, also with על. און, wickedness, is the absolute contrast of a pious and philanthropic mind; הוּת, from הוּה, not in the sense of eagerness, as Proverbs 10:3; Proverbs 11:6, but of yawning depth, abyss, catastrophe (vid., at Psalm 5:10), is equivalent to entire destruction - the two genitives denote the property of the lips and the tongue (labium nequam, lingua perniciosa), on the side of that which it instrumentally aims at (cf. Psalm 36:4; Psalm 52:4): practising mischief, destructive plans. שׁקר beginning the second line is generally regarded as the subj. parallel with מרע, as Luther, after Jerome, "A wicked man gives heed to wicked mouths, and a false man listens willingly to scandalous tongues." It is possible that שׁקר denotes incarnate falsehood, as רמיּה, Proverbs 12:27, incarnate slothfulness, cf. מרמה, Proverbs 14:25, and perhaps also Proverbs 12:17; צדק, Psalm 58:2, תּוּשׁיּה, Micah 6:9; יצר סמוּך, Isaiah 26:13, etc., where, without supplying אישׁ (אנשׁי), the property stands instead of the person possession that property. The clause, that falsehood listeneth to a deceitful tongue, means that he who listens to it characterizes himself thereby, according to the proverb, simile simili gaudet, as a liar. But only as a liar? The punctuation before us, which represents מרע by Dechi as subj., or also pred., takes שׁקר מזין as obj. with מזין as its governing word, and why should not that be the view intended? The representation of the obj. is an inversion less bold than Isaiah 22:2; Isaiah 8:22, and that על here should not be so closely connected with the verb of hearing, as 4a lies near by this, that הקשׁיב על is elsewhere found, but not האזין על. Jewish interpreters, taking שׁקר as obj., try some other meaning of מזין than auscultans; but neither זון, to approach, nor זין, to arm (Venet. ψεῦδος ὁπλίζει), gives a meaning suitable to this place. מזין is equivalent to מאזין. As אאזין, Job 32:11, is contracted into אזין, so must מאזין, if the character of the part. shall be preserved, become מזין, mediated by מיזין.

False lips - To false accusations and calumnies, which give him occasion and encouragement to do mischief.