The following phrases do not make what you're about to say better

[gremcint]

No offense but
I'm not a racist, sexist, heterosexist, etc. but
I'm not mad at you
I know it's not your fault
I know you can't do anything about it
With all due respect

[siead_lietrathua]

i find many of those phrases really depend on the context of the sentence.

"no offense but i think that perhaps there is an easier way to do this project"
"i am not being sexist, but i think your clothing (male or female) may be inappropriate for work"
"i'm not mad at you, i'm frustrated by your actions" (not the same emotions)
"it's not your fault, but i was hurt by XYZ. i know this wasn't your intention."
"i've had a rough day. i know you can't do anything about it, but i could just really use a hug"
"with all due respect, i think i would prefer to forge ahead on this my own way"

i know people throw the terms around willy-nilly or as excuses to be douches. i just think they have their proper place for use as well.

[Greenday]

Usually, those phrases are followed by something that negates what they are claiming they aren't. The majority of the time in fact. Just look at the website http://www.notracistbut.com/ and you'll understand. It's pathetic.

[PepperElf]

No offense but
With all due respect

Every time I hear that I now think about Boondock Saints 2.

[HYHYBT]

Sometimes it's a matter of knowing or suspecting that someone will choose to take offense and trying to head that off. "If something I say can be taken two ways, and one of them makes you sad or angry, I meant the other one." Even if, without the warning statement, you wouldn't realize there IS an other one.

[gremcint]

Ok I should add to the post that what I mean is saying that then being an asshole doesn't make you less of an asshole for adding that phrase.

[Rageaholic]

Or I'm not judging you but, (proceeds to make judgements about your character).

To people saying that, here's an idea: Don't say something that debunks the previous statement.

[smileyeagle1021]

Unfortunately, there are times when people need to use these phrases, because they really aren't racist/sexists/judgemental/assholes/etc.
"I'm not racist, but I would be interested to find out why there is a disproportionate number of African Americans in the American prison system." Assuming it is a true statement (I'm not up to date on prison population stats), that would be a valid question to ask without being racist, if there is a correlation that shows that there is some factor affecting one community over another, then it can be corrected, but even implying that such a factor exists (such as say many African Americans growing up in poor neighborhoods due to the after affects of segregation) somehow implies racism.
Alternatively, a real example was the professor who wanted to do a study on "if males and females learned math in different ways" who was immediately labeled a sexist. At not time did he say he thought men did better at math, or was his study in any way trying to prove one sex better than the other, but if there are trends where they learn differently this could be important information for educators so they could tailor learning to boys and girls based on whatever learning style was shown that each would be more likely to excel with... but implying differences apparently means implying inferiority. Which, going on a slight tangent, is bullshit, there is no question that men and women are different, I ain't going to be getting pregnant any time soon and my mother ain't going to get prostate cancer. Equality doesn't mean that everyone is exactly the same and identical, it means that they all have the same value, and speaking of math, 2+4+4 has the same value as 3+3+4.

[BlaqueKatt]

Which, going on a slight tangent, is bullshit, there is no question that men and women are different, I ain't going to be getting pregnant any time soon and my mother ain't going to get prostate cancer. Equality doesn't mean that everyone is exactly the same and identical, it means that they all have the same value

Unfortunately, equality has been hijacked by the same people that hijacked tolerance-and people have forgotten what the words mean.

[blas87]

"You're going to be mad at me, but"-

Constant phrase used by whiney bitch ex bf. Used before he was about to say something that didn't even bother or phase me. Like, he'd text me that, and then follow it by saying he wasn't coming to work that night. My reaction was usually

I've found most of the time, when people preface by saying "You're going to hate me, but-" or "You're going to be mad at me, but-" or "You're not going to like this, but-"........I've already put myself into apathetic mode.

[TheHuckster]

"You're going to be mad at me, but"-

Constant phrase used by whiney bitch ex bf. Used before he was about to say something that didn't even bother or phase me. Like, he'd text me that, and then follow it by saying he wasn't coming to work that night. My reaction was usually

I've found most of the time, when people preface by saying "You're going to hate me, but-" or "You're going to be mad at me, but-" or "You're not going to like this, but-"........I've already put myself into apathetic mode.

Homer: All right, Marge, I'll tell you, but first you have to promise you will not get mad.
Marge: I promise I will get mad, because I always do when you make me promise I won't.
Homer: All right, if you must know. Lisa and I have been gambling on pro football.
Marge: Homer!
Homer: You promised you wouldn't get mad!

[Lace Neil Singer]

I always find "just sayin'" to be a bit irritating.