For reference, here are the QL terms of use:
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Questionland is a tool for people who have honest questions, intelligent answers, and meaningful things to contribute. Questions, answers, and comments that are hateful, abusive or bigoted, trolling, deceitful, vague, confusing or nonsensical will be removed. We're also going to delete personal attacks and spam and any other crap that we deem to be inappropriate.
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In my small experience, when you explain to someone why his or her belief is nonsensical because it is based on things which are not true - which is something you and I both did on the homeopathy thread, for example - it frequently doesn't go well. Obviously, what a person believes reflects on who they are, and so it's not crazy to take it personally when I dismiss your beliefs.
That said, pointing out that a belief held by an individual is false is NOT an ad hominem attack, in and of itself. Nor is it intrinsically mean or rude to do so. It can be; I think it's mean/rude when you're pointing the thing out to a small child and the stakes are low (i.e., it's mean to tell a three year old that there's no Santa Claus), or when it's not invited and has no effect on you (i.e., walking into random churches and lecturing people in them about how creationism is lies). There are probably other situations, as well.
But Questionland is a public forum where people are supposed to ask questions, give intelligent answers, and contribute meaningful things. Asking and answering questions in a public forum that allows comments is a setting where it's neither mean nor rude to point out relevant facts, no matter how disturbing they may be to the deeply held beliefs of people reading the forum. That last bit bears repeating: just because someone's deeply held beliefs have been challenged by something you said, does not mean you were rude or engaged in ad hominem. No one has the right NOT to have one's beliefs challenged in public.
Nearly everything you've posted in this thread (that I've read) meets my definitions of "intelligent answers and meaningful things to contribute". I also do not think that repeatedly and stating facts - even forcefully and/or snarkily - constitutes "abuse".
The only question, then, is one of tone. Your tone may have veered close to the snarky from time to time. If you feel unsure, then do an editing pass through your posts to tone down snarkiness before posting - I try to, although I don't always succeed.
I would challenge anyone to point out something hateful, abusive, or bigoted that you've stated, however. Moreover, you've at least once gone out of your way to show respect for people with whom you have fundamental disagreements: you were specifically respectful of sphinxemmashade's personal experiences in the Nurse thread on cranio-sacral therapy.
So I think you're doing great, and keep it up.