On one hand, blackouts, memory repression and euphoric recall account for the appearance of lying. On the other, there is no more underhanded way to exercise control over others than by lying. This is just another way to inflate that massive ego. As observers, we will unlikely be able to distinguish between these lies, but this is not necessary. As the degree of either suspected or actual lying increases, so does the probability of substance addiction.
Distorted perceptions explain impaired judgment.
Before we can judge, we must first perceive. We then use these perceptions to form judgments. If our perceptions are distorted, our judgments are based on inaccurate information. If an addict perceives that you have cheated on him, he not only makes an accusation that is false, but when you deny it, he will judge you a liar. The judgment itself becomes, by definition, impaired, explaining much of the bizarre behaviors of substance addicts.