To dream of spit represents an attribute or quality that you should discard. It may also signify hostility and defiance.
To dream of back biting indicates that you may need to consider your current actions as they are risking harm to another. Someone back biting you suggests that family issues may be in your future.
To dream that you have malice toward others implies that others will perceive you negatively due to your inability to express your hostility in an appropriate manner.
To dream that others have malice towards you indicates that someone close to you will betray your trust.
To hear a rapping in a dream suggests that you have fear of an approaching confrontation. You may be experiencing guilt which you're afraid may be catching up to you.
To dream about mucus generally symbolizes something that is burdening you that you may not be willing to vocalize or speak out about right now. This secret or thought is unhealthy for you to hold in, like as we know it is better to spit out mucus than to swallow it back down. Your subconscious is telling you to share your story, secret, or an opinion that you may have about something, since you are currently letting it affect you in a negative way.