It is significant that the word "wicked" does not necessarily mean morally depraved or violently dangerous. It is essentially synonymous with "ungodly" and the Hebrew word (rasha) used here is often so translated. This tenth psalm provides a graphic summary of their real character. They are:
(1) Proud. "The wicked, through the pride of his countenance, will not seek after God" (v. 4).
(2) Fawning. "For the wicked . . . blesseth the covetous, whom the Lord abhorreth" (v. 3).
(3) Atheistic, at least in behavior. "He hath said in his heart, God hath forgotten: . . . he will never see it" (v. 11).
(4) Stubborn. "He hath said in his heart, I shall not be moved: for I shall never be in adversity" (v. 6).
(5) Profane. "His mouth is full of cursing . . . : under his tongue is mischief and vanity" (v. 7).
(6) Hurtful. "In the secret places doth he murder the innocent" (v. 8). This surely applies to character assassination, when not to actual killing.
(7) Deceptive. "His mouth is full of . . . deceit and fraud: . . . He lieth in wait secretly as a lion in his den" (vv. 7, 9).
It is significant that the apostle Paul cited verse 7 ("full of cursing") as descriptive of most of the ancient pagans in his day, and it can sadly be applied to many modern pagans as well.
But David said: "I have seen the wicked in great power, and spreading himself like a green bay tree. Yet he passed away, and, lo, he was not" (Psalm 37:35-36). "For the Lord knoweth the way of the righteous: but the way of the ungodly shall perish" (Psalm 1:6). HMM http://www.icr.org/articles/type/6/