If you have to preface what you are saying with "I don't mean to offend you"

Sometimes, one can not know what the other person might perceive as offensive, but wants to make a point and adds "No offence" at the beginning of the sentence just to be perfectly clear.

If someone becomes negatively affected by the phrase "I don't mean to offend you" that's on them.

Example "No offence, but isn't a better rush than ?"

why am i being downvoted for what you should do

Hey Ear

You're not wrong

Or just say it without making it clear that no offense is meant

I don't mean to offend you, but catgirls are cute.

Because perhaps you are far to easily offended. I swear people think that being offended just means that they're right