Galatians 5:16-18
16 I say then: Walk in the Spirit, and you shall not fulfill the lust of the flesh. 17 For the flesh lusts against the Spirit, and the Spirit against the flesh; and these are contrary to one another, so that you do not do the things that you wish.18 But if you are led by the Spirit, you are not under the law.
You can't blame grace for sin. Those, rare, examples of people sinning and using grace to justify it, indeed do not understand grace, and may not even have it. As I said, "Sin shall not have dominion over you, for you are not under law but grace." I'm sure the same people using grace as an excuse to indulge in sin, would do the same in the OT times by sacrificing animals and using the blood of bulls and goats. They would sin and then sacrifice, and continue to do it, so as to live in their sinful indulgence. Licentiousness is not something you can attribute to grace, in so much as purposely having sin dominate your life. That is not what grace teaches, but indeed if you do sin, grace abounds.