I find that disdaining and lamenting the prevalence of "political correctness" in our society is usually just a method that people use to justify ignorant and unimaginative word choice.
I would take a somewhat opposite view. I think that much of the time political correctness is used in an effort to silence people who disagree with a given viewpoint. I think that likewise a significant portion of claims of offense at what someone says are feigned, and that "offense" is brandished like a weapon. People pounce on comments that are likely benign but can be construed as possibly racist/bigoted because they see it as an opportunity to smear their opponents. I think that this generally devalues actual racist/bigoted acts in a "boy who cried wolf" kind of way. I also feel that labeling a person or persons as racist or bigots based on the possibility that it might be true is as offensive as actual racism/bigotry.
I will take the opposite side to your opposite view. I don't like the term "PC." I feel it is used by people who either want to say something they know offends others, as a way to disclaim what they are saying, or have just said something offensive, as a way to say "Hey, I'm not at fault. You're just being PC. You aren't really offended." And yet that is incorrect, because I'm actually offended by what stereotype/slur you have said. So, in addition to being offended, I'm told that my feelings are wrong/fake/contrived.
First of all, you're choosing to be offended by my comments. I used phrases like "much of the time political correctness is used in an effort to silence people" and "a significant portion of claims of offense at what someone says are feigned". Clearly I didn't say "all of the time" or "all of the claims". In fact I was careful enough to use phrases that didn't automatically imply most or even half. Clearly your genuine feelings of offense would leave you outside that significant portion who aren't genuine. Yet you chose to not only take offense but to label my observations as stereotypes and slurs.
I would also disagree with you about the threshold of what constitutes political correctness. You're talking about people who wish to make comments that they know will be perceived as offensive. I'm talking about people being labeled for making comments that could possibly be construed as insensitive even though there are equally plausible ways that the comment could be otherwise seen.
What I'm saying is that the term "politically correct" is not a positive term. It is one that is mostly used to shift the argument, like so:
Person A: [insert offensive statement here}
Person B: Hey, that's offensive!
Person A: Stop being so PC.
In this case, person A is not addressing what he or she said, but is instead questioning the motives of Person B in being offended. Person B could be legitimately offended, but now isn't allowed to be. Often this goes accompanied by some accusation of "choosing to be offended", as if taking offense is now a conscious decision, as opposed to the reaction it normally is.
Sometimes, you can also see it used like this:
Person A: [offensive statement]
Person C: Oh, that's not PC. Person B will come after you now.
Still, we haven't dealt with the nature of the offensive statement, or that it's wrong, only that Person B will nefariously take offense.
Sometimes, it can be used this way:
Person A: I can't say what I'm thinking because it isn't PC, but [insert semi-offensive statement that plainly alludes to something more offensive.]
Now person A gets away with being offensive, while criticizing those who take offense, and at the same time not using the worst language, but only obvious substitutes.
My point is that calling someone "politically correct" doesn't move a conversation forward at all, but merely requires the offended person to show that their offense is real, and not a form of puffery. It shifts responsibility for being offended from the person who uttered the original remarks to the person who heard them. It is also very often used against someone (like me in my prior post) who takes offense about the statement even though it isn't directed at him or her, but at a third party, as if it's wrong to be offended on someone else's behalf. This is why I very much dislike the phrase and don't use it any more.
You're missing other common cases in your examples though.
Person A: [insert innocent statement here that can possibly be construed to sound politically incorrect]
Person B: Hey, that's offensive! Person A just made a bigoted/racist remark and needs to apologize for it.
Person A: [insert something that isn't racist at all]
Person B: Person A is using "codewords" to hide the racism/bigotry in their stance.
Person A: [insert something that isn't racist at all]
Person B: The only reason Person A would say that or hold their stance is because they are racist/bigoted.
I agree that "politically correct" isn't a positive term, but political correctness is used to shift both ways. Your examples happen a lot, so do mine. In fact there can be real and feigned offense for the same innocent or nefarious comment.
Because I don't think we completely disagree, I'm going to sign off from this pleasantly respectful debate after airing these thoughts, because I have exams I should be studying for.
I understand that there are people who feign offense. As someone who is sometimes actually offended, these people anger me, because it causes others to question my motives when I'm offended (of which there aren't any, I'm just offended.)
But where I think we're talking past each other is that the events you're describing aren't people using the term "PC", but rather engaging in a behavior that you ascribe to being PC. Frankly, I think the better way to handle this is not to call them PC, but to explore the roots of their offense, and see whether these roots are real or fake. The word ignorance has an overly negative connotation unfortunately, but sometimes we all can be ignorant about what is offensive, and what isn't. What might be racist or sexist, and what isn't. And it goes both ways, people can certainly be overly sensitive. It's tough.
Still, if you (and when I say "you" I don't mean you specifically, but the plurality of anyone reading this post, including myself upon re-reading this later, because I think using the word "one" all the time can sound overly pretentious) -- if you find yourself in a situation where someone takes offense to something you or someone else has said, and you don't see where they're coming from, initially apologize (if appropriate) but then try to find out why it's offensive. Maybe you'll discover, "oh that actually could be offensive. I should stop saying that." Or maybe you'll learn that this person is just trying to make a scene, and you can go from there (now using "PC" against someone who is engaging in this behavior you decry.)
As an example, I used to say "gypped" all the time. Probably for decades. I had no clue of it's origins, and no one else I knew was offended by it. It was just a word I meant when someone or something cheated me. One day, someone confronted me on that word. Why? Because it's derogatory towards Gypsies, a group of people who have experienced some of the worst discrimination, persecution, and genocide as any in Europe, and still do to this day. I had no clue about the origin of the word. In my head, I even spelled it "jipped". I completely see why the word is offensive, and even tho I don't know any one of Gypsy origin, there is no reason at all to say it. I wasn't being malicious or rude when I had been using it before, but it doesn't mean it was the correct thing to say, and intent doesn't always matter. People still had a right to be offended by it, and a right to tell me so. I'm glad I learned what I was saying, so I could stop saying it. Now I wince when I hear it, and depending on the situation, will speak up if possible.
I tend to believe most people are honest. Maybe that's where we disagree. But if someone says something is offensive, I will not only take them at the word, but try to learn why, so I can change my behavior. Certainly there are a few political commentators and politicians who engage in the behavior you describe, but I think they are far and few between, outside of politics. More likely something that I was ignorant about was actually offensive, and it is much better to avoid kvetching about political correctness, and instead learn what I did not know before.