When people start what they are about to say

[Angelicinnocent]

With "I'm not being funny but" or "I've no wish to be rude but" what they actually mean is that they are going to be extremely rude or insulting. Have heard this said about 6 times today by different people and not directed at me so unable to reply

Agree. Like 'I'm not being racist but'

Yes Donald that one too

Oh god the "I'm not being racist but... " drives me up the wall. Clearly you are as you wouldn't have the need to follow it with that!
I don't want to be rude but... yes clearly you know what follows is going to cause offence!!

My MIL starts quite a lot of sentences with 'I know you won't mind me saying, but.....'

So glad it's not just me.

Yup, if you have to clarify you're not being rude then you're being rude

It means "I'm going to insult you but I was dragged up by a feral pack of dogs, so I think this shitty clause constitutes manners."

Yanbu
'I am not being funny but...' comment really makes my skin crawl

"With all due respect" is another.

I mean this kindly....

Nope, you don't

Im with you op!

Also "No offence but [insert obviously offensive input here]"

If you don't mean offence you wouldn't say no offence that already suggests it will be offensive...... lol

I'm no prude but....

The worst one is 'with respect' or 'with all due respect' both mean that the person has absolutely no respect for you or your opinion! Really pisses me off.

I don't think that's always the case.

A colleague commented on something I did today with "I don't mean to be rude but...", and what they followed it up with wasn't rude; it was simply something that had happened that I'd not noticed but they had.

They just didn't want me to think them rude for pointing it out. Which I didn't.

I get a lot of "I hate to say this but". Don't bloody say it then!!

MIL special 'I'm not trying to tell you what to do but...' followed by useless advice.

I hate 'Not being funny, but...'. Irritating as fuck.

Also see 'Don't get mad with me, but...'

Invariably means they're about to step waaaay over the line.