Outward appearances can tell us much about a person...

Not that which goeth into the mouth defileth a man; but that which cometh out of the mouth, this defileth a man. [18] But those things which proceed out of the mouth come forth from the heart; and they defile the man. [19] For out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies...Matthew 15:11, 18-19 KJV

Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles? [17] Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit. [18] A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit. [19] Every tree that bringeth not forth good fruit is hewn down, and cast into the fire. [20] Wherefore by their fruits ye shall know them. Matthew 7:16-20 KJV

Sometimes the outward appearances can be deceiving...

Woe unto you, scribes and Pharisees, hypocrites! for ye are like unto whited sepulchres, which indeed appear beautiful outward, but are within full of dead men's bones, and of all uncleanness. [28] Even so ye also outwardly appear righteous unto men, but within ye are full of hypocrisy and iniquity. Matthew 23:27-28 KJV

Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven. [22] Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works? [23] And then will I profess unto them, I never knew you: depart from me, ye that work iniquity. Matthew 7:21-23 KJV

The most impotant thing to remember is to not use your liberty to cause others to stumble. Stay above reproach...

It is good neither to eat flesh, nor to drink wine, nor any thing whereby thy brother stumbleth, or is offended, or is made weak. Romans 14:21 KJV

Prove all things; hold fast that which is good. [22] Abstain from all appearance of evil. 1 Thessalonians 5:21-22 KJV

Use your liberty instead to serve others...

For, brethren, ye have been called unto liberty; only use not liberty for an occasion to the flesh, but by love serve one another. Galatians 5:13 KJV