I know I am guilty of saying all, never and should. I try to be careful to not do it. But of course I don't always manage it. Most groups online or offline, tend to get some that feel their way is the one true way. The "You should never...." or "All dominant should..." and FetLife hasn't been any different.
But over the years I have found that I don't always need to state my opinion. It has become a matter of letting go of the need to be right, need to prove myself or whatever the feelings were at the time.(They are hard things to own up to and of course I don't always succeed at it but try hard.) So I try hard not to feel like I need to state how it is in my relationship just because the original post doesn't fit how we do things. I try to stay on topic.
If I do feel I can add something to the discussion, I can disagree politely without putting another down. There is a difference between stating how it is in my relationship and implying everyone who doesn't do it our way isn't doing it right. There is a difference between sharing my experiences and preaching to others that don't do it my way that they are unsafe, wrong or insane. There is a different between "this is how we do it" and "this is how everyone should do it." There is a difference between saying, "in my relationship I have to...." and "as a slave we all should be....fill in blank... and if you don't you aren't really a slave.".
When someone posts something I wouldn't do and is asking for advice, I don't feel the need to tell them they are wrong. Because for their relationship obviously it isn't wrong. Plus I know that opening up and sharing can be hard so making others feel bad just closes them up. If I want to help others through my experiences - closing them up won't accomplish that.
So when someone asks for advice for something I wouldn't do or disagree with I try to do one of a few things -- stay out of it since it doesn't apply to my relationship. Or I try to give them suggestions on how it applies to their relationship. Or I share my experience in relating to the topic in a very clear factual way without emotions and without making judgments on how they do things. Maybe I can suggest a link, a bit of advice or a book that might help them. But if I don't have actually anything useful to say - well then I am not going to say anything. I try to remember even though I might not agree with it or would never do it in my relationship doesn't mean I always need to chime and state that because there are so many posts eventually a topic that is fit for expressing my opinion (despite if I agree or disagree) will come up for me to reply to. Because if my reason for wanting to post is to share my experiences for others to learn from then eventually I will be able to state that opinion in a relevant post that deals with the topic. Which will make it more receptive to people. And hopefully then others will read it and get something from it. But I doubt saying, "well I would never do that because as a slave disobeying just never crosses my mind and anyone who does that isn't really a slave or is just a wannabe" helps anyone. It doesn't state anything worth anything to anyone. Not even myself. It is offensive, condescending, negative and implying that others that do anything different then I do -- is disrespectful not only to the original poster but to Master. It isn't a good reflection of him to be feeling the need to be so superior.
I really try to remember to treat people how I want to be treated. If I asked for advice on a forum and everyone was telling me I am doing it wrong, I know how that would make me feel so I try hard not do that to others. I try to remember that just chiming in to chime isn't a good reflecting on Master. Because he wouldn't want me to make others feel inferior or bad that they did something another way. And really it is a just a lot of a wasted time and energy that could be focused elsewhere - like on Master and my service to him.