If you have to start a sentence with
"I don't mean to be rude, but..."
"No offense, but..."
"Not to be mean, but..."
"I mean no disrespect, but..."
or really any sort of
"Qualifyingstatementhere, but..."
STOP. Really, I mean it. Stop. Don't finish that sentence. Because you sound like an ass. Really. If you have to stop and qualify what you're about to say, think for just one second about how you would feel if it were being said to you.
If you're totally okay with sounding like a complete asshat, go ahead. Continue. But drop the disclaimer; it's really just pointing out what a tool you're going about to be.
Oh, and special attention should be paid to
"I'm sorry, but..."
and
"I'm sorry you were offended, but..."
if this is an apology. That is not an apology. If you are qualifying your apology with something like "I'm sorry but you're wrong," You're not sorry. You're sounding condescending. If you're qualifying your apology with "I'm sorry you were offended, but..." you're not actually sorry about what you did at all. Even if you think you're in the right. Even if you think offering a hollow apology is better than nothing. Guess what? It's not. Because you're not acknowledging anything that you may have done to cause pain to another person, and you're not accepting that your actions have consequences.