The trick is that gratitude and weariness are contradictory, which falls under the umbrella of what sarcasm provides; a way of expressing gratitude in such a way that weariness shows. The reaction of annoyance/unpleasant surprise this causes on part of the receiver of sarcasm is anticipated by the speaker, and is considered a way of wounding them, which is why sarcasm can be used in arguments.

While both your intention and the conventional intention are both valid, the conventional intention is triggered, as the basic structure of expressing the spirit of one emotion with the letter of another is more commonly used, and thus more frequently recognized as such.

From Gwern's notes:

Polyamory and Asperger Syndrome

Anapol 2010 featured an interesting section on Asperger's syndrome anecdotally correlating with polyamory - which LW has often been accused of being host to; as this is the only print discussion I know of, I will take the liberty of quoting the entire thing:

Asperger syndrome has been relatively recently recognized as a neurobiological disorder somewhat related to autism but characterized by deficiencies in social skills, difficulties with transitions, and difficulties reading body language and other nonverbal cues. Often there is also acute sensitivity to sounds, sights, tastes, and smells and exceptional skill or talent in a specific area. These people are known both for their eccentricity and for their creativity. Einstein, for example, has often been mentioned as a likely Asperger’s candidate. Because of the legendary inability of people with Asperger’s to navigate social situations and function well in intimate relationships, I wouldn’t have expected to find them gravitating toward polyamory, which, as we have seen, thrives on emotional intelligence and excellent communication skills. Nevertheless, serendipity has brought this connection to my attention. Within the space of one day, I discovered that three different people who I’d been interviewing for this book either had been diagnosed with Asperger’s or had a poly lover with Asperger’s. Considering that Asperger’s is thought to be rather rare, I found that significant. When I started reflecting on people I had known, including some of my own partners, I began to notice a common pattern. I began to suspect that a significant minority of people choosing polyamory have Asperger’s traits if not the full-blown syndrome.

I asked one of my interviewees who identified himself as having Asperger’s how he would account for polyamory and Asperger’s being such unlikely bedfellows. His opinion, based on his own life experience, was that Asperger’s leads to a technical and strategic way of consciously thinking that is applied to relationships as well as other areas of life. Okay, I thought, so polyamory is more strategic? Perhaps it could be, but only for those of very high intelligence.

Tanya, who suspected that her partner Jerry had Asperger’s, directed me to Dr. Amy Marsh, a sex therapist specializing in working with Asperger syndrome (or Aspies as they are affectionately nicknamed). She told me that she had studied Aspies and sexuality for her doctoral research and found that a number were involved in polyamorous relationships. Why? She guessed that “Aspies gravitate toward intimate situations where there are rules, mutual agreements, parameters, defined roles, and ways to manage their own limited capacities for emotional engagement but still enjoy intimacy (mostly on their terms). . . . My sense is that Aspies will be among those who approach these things in a more formal way than others.” She mentioned polyamory as one of several other intimate structures that have this kind of appeal.

This explanation seems to be in line with the strategic thinking concept, but I have another hypothesis. Because Aspies are fairly clueless about social norms and prone to misread or overlook negative reactions to social deviations, they are less likely to be bound by mononormative relationship expectations and more willing to experiment with out of the box arrangements. They don’t automatically reject polyamory as socially incorrect as some might do. Instead, they take an unbiased, objective look and decide it may meet their needs. And then they’re not bothered by social ostracism because they either don’t notice or are used to it because of their other odd behaviors. Additionally, polyamory may make intimate relationships more manageable for them if their partners can meet their own needs for empathy and emotional closeness, which the Aspie may find bewildering elsewhere.

To clarify, the two ideas (correlation with nerdiness and correlation with social skills) are both equally poor, there's no reason to use one and not the other.