to think if you start a sentance with "this is going to sound really rude" then you probably shouldn't say it

[autumnmum]

That's it really. Someone I had only just met started a conversation with me using this opener today, and then was suprised when I was upset by what they said.

[cumfy]

Perhaps more pithily:

I totally disagree with what you're saying, but completely recognise your right to say it

[quesadilla]

Depends... if its with someone you know and trust and you're being frank about something important and you're having a drink it can be fine. If its an opener to a conversation with someone you hardly know, nine times out of ten its best just to keep it to yourself.

[autumnmum]

Thanks for your helpful replies people - you've made me feel a lot better. I spent all last night thinking of witty things I could have said.

cumfy not a religious sect, just a run of the mill environmental charity. I have discovered today that the person in question is training to become a therapist!

[bradyismyfavouritewiseman]

I think it depends. Sometimes something needs to be said. Its going to come across as rude.
Especially in text, email etc.

I refuse to say it now though.

My auntie thinks that if you start a sentence with 'with all due respect..' you can say what you want.