Excuses can ruin true communication if it becomes a habit because it can cause the person on the receiving end to see you as not persistent, not a promise keeper, not a person who follows through with what they say, etc.
Boasting can ruin true communication if it becomes a habit because it can cause others to dislike you. If you brag and boast all the time about things or people you have/seen and others haven't, it can turn people sour. For example, if I kept bothering you about how my computer was better and newer than yours, you wouldn't like it would you?
Always apologizing can ruin true communication if it becomes a bit because it can be so repetitive, people may become suspicious. They might not know when you're actually sincere about your apology, or whether you're just saying sorry again out of habit.
