The thought in these verses is the secret partiality a man has to his own sin. Like someone who keeps some tasty morsal hidden in his mouth which he conceals from others, and who privately enjoys the taste though no one else knows what he is doing, so the hypocrite secretly relishes his sin.
Zophar attempts to prove that Job was not a true man of God, because even while he seemed to live uprightly, he still had a taste for sin. He always had a struggle resisting temptation. These things are proving now that you don’t belong to God. We have an old nature – but Satan uses this temptation to try to prove there is no spiritual life in us. When we are buoyant, it is easier to answer his suggestions, but when we are cast down, the devil can put his finger on our failings. The depressed person may feel they still love their sin. The severely depressed person fears that they turn even preaching to their personal advantage.