Your vs. You're

The inability to differentiate between your and you're is probably one of my biggest pet peeves. While I'm not a strict prescriptionist - I think language does change over time and we have to be aware of this - using your for you're (or you're for your) is one grammar mistake that I cannot condone. I have heard the argument that as long as you understand what the other person is trying to convey, then it does not matter how that person chose to express their point.

However, I recently came across a very poignant example of why you should never mix up your and you're. As you may recall, we language nerds had a blog called The Grammar Vandal as one of our blogs of the week. Well, the Grammar Vandal published a post called, "She got what she deserved." This is only a part of what she wrote (please visit her site for the full post, and a chance to vote on whether this person really got what she deserved):

This is my new favorite entry on my new favorite Web site, fmylife.com:

Today, I was flirting via text with a coworker. Things started getting heated, and I wanted to send her a sexy picture. I asked if she had any suggestions. She said, “Your nuts!” She meant, “YOU’RE nuts.” I sent her a photo of my junk. I offended a co-worker with incriminating evidence. FML

Okay. We know this guy isn’t the sharpest tool in the shed. Anyone knows you don’t send naked pictures to someone you barely know. And I’m going to assume that these two people are over the age of 18, because if not, that’s a different issue altogether. Assuming they both are above the age of consent,

That girl got exactly what she deserved.

She mixed up “your” and “you’re” and thus was blinded with an image of the least attractive part of the male anatomy, an image that will likely stick in her mind for quite a long time.

The vast majority of the time, using "your" when you mean "you're" probably won't produce a result such as the above example. But I think it offers a quality reason why you should practice proper grammar - if you're not careful about what you say, it could take on an entirely new and unintended meaning.

Does the mistake of using "your" for "you're" bother you? Also: what do you think has contributed to using your (possessive) for you're (contraction of you are)?