"This is especially true of those who follow the corrupt desire of the sinful nature and despise authority. Bold and arrogant, these men are not afraid to slander celestial beings; yet even angels, although they are stronger and more powerful, do not bring slanderous accusations against such beings in the presence of the Lord." NIV translation
Peter explains that there are those who follow the sinful nature and will not accept correction. They despise those that God has placed over them and are arrogant enough to even accuse celestial beings. Although we may not like some of the things that leaders say and do, we must accept the fact that God is in control and, if He did not want them in their positions, He could remove them.
"But these men blaspheme in matters that they do not understand. They are like brute beasts, creatures of instinct, born only to be caught and destroyed, and like beasts they too will perish." NIV translation
The men described are like wild beasts in that they have no respect for any authority. They speak against the authority that has been granted by God and so, like the beasts described in Revelation 19, they will be dealt with at the coming of the King of Kings.
"They will be paid back with harm for the harm they have done. Their idea of pleasure is to carouse in broad daylight. They are blots and blemishes, reveling in their pleasures while they feast with you." NIV translation
These false teachers will be dealt with by God as they have caused many people to stumble. We see here that these people try to have it both ways as they delight in sin but show up at the gatherings of believers when it is time for a meal. We are a new creation when we accept Jesus and receive the Holy Spirit. This new creation does not belong in the old situations of sin and we cannot be comfortable in them.
"With eyes full of adultery, they never stop sinning; they seduce the unstable; they are experts in greed - an accursed brood!" NIV translation
Although these false teachers may have brief periods of time where they are not actually engaged in the physical sin, their eyes never stop lusting after the flesh. This, too, is a sin and they get others that are not grounded in the Word of God to go along with them. To them there is never enough as they constantly hunger for more of the sin. They are cursed for today because of the consequences of their sin and they are cursed for eternity in hell if they do not repent.