i know what your saying, but sometimes being a tad harsh is the only way you can say the thing you are trying to say. it doesn't mean that the person that is saying "no offense" is trying to get you down. but is more or less saying he has thought about what he will say and has realised that it will/can be taken the wrong way. hense the "no offense" to guide the reader in the direction the comment was intended to mean.