Think about this; when you open your mouth and sarcasm comes out, what does that communicate to the person you are talking to? It communicates that you are hurt about something and you're possibly being defensive about something. When someone tells you that your are being sarcastic and what's coming out of your mouth is offensive to them, and you're response is "No I'm not", "No it's not" or "I didn't Mean anything by it." Consider this, "Yes you are, and yes you did mean to hurt that person," that is why you said it to begin with. Most times, when we speak out of emotions, we are revealing what our hearts truly feel.
There are some people that struggle with thinking positive or saying positive things for many reason. Maybe throughout their journey they've been hurt, or put down. When you behave in like manner, it reveals what's really going on inside of you. When the going gets tough, take some time out to regroup, and talk with the someone you trust. Ask for guidance and help. We don't always think so, but just maybe a change is needed. Use your words in a positive way. Use your words to encourage, strengthen and build others up. Words are powerful. They could either build you up, or tear you down. Are you building people up, or are you tearing them down by what you say? Think about it. Sarcasm hurts!!!