Aside from being a dandy, complete with his trendsetting wardrobe, clueless life, and irresponsible nature Lord Arthur, Viscount Goring, has a redeeming quality that makes his defects pale in comparison: the love and loyalty that he renders to his best friends, Sir Robert Chiltern and Sir Robert's wife, Lady Chiltern.
When the enigmatic and malicious Mrs. Cheveley enters the Chiltern's home, she does this with the purpose of blackmailing Sir Robert. Sir Robert is about to give his vote against investing on an Argentine Canal project. Mrs. Chevely has invested greatly on the project and wants Robert to vote in favor of it. If he does not, she threatens with exposing Sir Robert's past which, if done, will affect him greatly.
The reason is that Sir Robert has a secret: he made his fortune and built his good and incorruptible name through what, in modern vocabulary, is referred to as the while collar crime of inside trade information.
Basically, a younger Robert Chiltern, when working as a secretary for Lord Radley, obtained inside information about a government trade that was about to occur. Investing in that plan would bring a tremendous revenue to the investor. Robert Chiltern sold the government secret to Baron Arnheim. As a result, the Baron became very rich and made Robert partake from his fortune. What this means is that Sir Robert is by no means "an ideal husband". He may be so in the eyes of his wife but, in real life, he is a man whose name and fortune is based on crime.
Although Lord Goring is not pleased to know that his friend would have been capable of something like this (Sir Robert explains that his crime is a symbol of courage and not cowardice), he still realizes that Robert's life will come spiraling down if Mrs Cheveley discloses his secret.
A natural charmer, Lord Goring takes advantage of Mrs. Cheveley's need to be married to soften her demeanor. After all, they once were engaged to marry, and then their engagement it was broken off, althouh the reader does not yet know why.
The way in which Lord Goring shows his friendship is by waiting for the right moment to expose Mrs. Cheveley's theft of a bracelet that had belonged to one of Lord Goring's relatives. This occurred during the time that they were engaged. This is the reason that it is assumed that Lord Goring and Mrs. Cheveley never married, and she disappeared.
The fact that Lord Goring is persistent in waiting for the perfect moment to act against Mrs. Cheveley brings out the true nature of his character. Despite of being a "good for nothing" like his father says, at least Lord Goring shows loyalty and keeps his calm when Robert accuses him of plotting with Cheveley against him. He shows devotion and goes in action for his friend in good and bad times. Out of all the other characters, the otherwise shallow Lord Goring proves to be the most solid of them all.