There are certain phrases that sound like you are being very respectful when, in all actuality, they are very rude and meant to be insulting. You know which ones they are because you have used them on a number of occasions. I don’t know who the first person was who coined the phrase “no offense,” but he/she was a jerk. In essence, when you premise a statement by saying “no offense,” you are preparing that person to be insulted right then and there.
Example: No offense, but you are a stupid dummy.
It’s the “but” that lets you know it’s coming. Another sneaky one is “with all due respect.” This one sounds more distinguished and eloquent, but it is actually worse than “no offense” because you are basically telling the person that they deserve no respect whatsoever!
Example: With all due respect, ma’am, you are a stupid dummy.
Notice the use of “ma’am” in that example. It’s kind of like slapping someone with a glove (like in the old days).
The bottom line is this: when you start off a sentence with “no offense,” you are preparing them to be offended. When you begin with “with all due respect,” someone is about to be disrespected. It kind of cuts a little deeper when you set someone up and then smack them down. So, with all due respect, unless you know how to use these phrases, don’t. No offense, reader, but it doesn’t seem like you are capable.