How can I say something potentially offensive about someone to them - but without offending them?

"I'm really impressed with your ability to stick your position regardless of the evidence."

The premise of your question is that you are saying something offensive. Which means that it is likely to offend, regardless.

Sometimes is not how you say it but rather when you say it. Oftentimes people are aware of their own problems but are in denial and pretend they don't exist. When you point their problems out, they won't be thankful, they will be pissed. Maybe it might be a wake-up call for them, but that won't happen until long after they have digested your words. It's another story if people come to you seeking for advice. They acknowledge their problems, they just don't know how to deal with them. They are willing to hear what you got to say, and even if your feedback is tough they will take it and ponder on it. Less likely to be offended, because they came to you and not the other way around. How you say it is important too. You don't want to be passive-aggressive, you don't want to be too preachy, but you definitely want to be giving constructive criticisms. It would also be better if you yourself had similar problems. Point is, let them feel that the feedback comes from a place of love and concern, and that it's not an attack against them. If you don't know how to be constructive, then might as well keep your mouth shut.

Understand that the received message may differ from the one you thought you sent.  It may differ vastly.  You must accept that.  And potentially move on.  Because ultimately the received message matters most in the mind of the receiver, your intentions matter little.

More so than approach I'm concerned about your motive. If your motivation for having these conversations is that you care and are concerned about the person them start with that concern not your diagnosis. That would require compassion for the person. What you've typed as examples sounds a lot like someone who just wants to give someone a piece of their mind. That's the wrong attitude and I'd encourage you to check your motives at the door. Abuse, broken homes, lack of direction and over sensitivity are all serious issues that can't be resolved in one conversation. They require that the hearer process the problem fully (its  origins and seeing its affects on their lives and a decision made to change) before action can happen. So maybe starting with questions rather than a preachy arrogant diagnosis would be better. "Why do you think you haven't taken action on any of your goals yet?" "Where do you see your life headed in the next 5 years?" "What affects do you think your abusive relationship has had on your current relationships?" "Do you believe that coming from a broken home has prevented you from trusting?" Questions open the door to dialogue or they let you know the person isn't ready to engage on the topic. It's not your right or responsibility to go telling people the hard and offensive things just because you think it's time.

You focus on the behavior, and its effect on you, specifically how it creates a conflict-of-needs. You craft and deliver it in such a way as to create a conversation and one that invites them to reply constructively to you - not to defend themselves or weather abuse. So e.g. "You keep doing X. You know X drives me nuts, so this comes across as utterly disrespectful. What are your reasons for doing X? What reason do you give yourself for not stopping doing it?" - distinguish the person from the behavior (this can be hard sometimes). You can love the person and hate the behavior. - avoid labeling people or behavior. Focus on the effect, the consequences. e.g. don't say 'Your flagrant lack of initiative', say 'You don't seem to me to be showing initiative' - avoid imputing motives; describe your perception as a perception, not laying down absolute fact (Don't say "You have no goals". Say "From where I'm standing, it seems you have no goals" or "I don't get the impression you have goals") - never put the person down, no matter how annoying/dishonest/disrespectful/.. they are. Be mindful if they escalate the emotional tone in defense. - don't use sarcasm, at least not directed right at the person's personality or identity (and not their behavior). Don't ask a question unless you genuinely want to hear the answer. If you're not interested, then you're just expressing frustration, or anger - which is also ok, then just be honest and say that. Better to say "I'm really annoyed/disappointed you did Y" than "What is your major malfunction, numbnuts?!" Having said that, this one is perfectly right: "I recognize you just got out of an abusive relationship, but that does not entitle you to play the victim for the rest of your life and expect others to take pity on you." except I wouldn't add the "You need to grow up". Ask for their reaction instead. (They will presumably disagree with your characterization, and that's where a potentially constructive conversation can begin). PS recommended book http://www.amazon.com/Crucial-Confrontations-Resolving-Promises-Expectations/dp/0071446524

You can work as hard as you like on your message, but you can't control how it will be received. That is totally up to the other person. If you must say it, reduce its offensiveness using the other tips given here, wait for a good moment, then deliver it. The recipient will either be offended or not. You cannot stop them from feeling as they do.

What you are asking for is called a backhanded compliment.  http://en.m.wikipedia.org/wiki/Backhanded_compliment Snobby people have this amazing capacity to give you an insult and make it sound like a compliment. http://bertc.com/subfour/truth/putdowns.htm

I think this is intolerable. Others do not know what a unique experience was like for you an drawing a conclusion to a behavior now is useless. It's offensive, it's often entirely unbalanced and lacks all nuance. Wow. It's so entirely wrong that I'll need to return to edit this to include a more thoughtful explanation. Useless opinions that may have touched on a fact and the conclusions are only those of the person stating an offhand criticism. Terrible, hurtful and unimportant. I would not tolerate such a vainglorious self-righteous person in my life.