What do you do about the deliberately contrary poster?
This particular person sounds rather annoying, especially if she gets snippy or is condescending in her replies. I think ignoring her is the best response, and if possible, posting something that does
answer the OP's question, so the OP doesn't feel like this one contrary person is the only voice out there.
In general, though, I think sometimes people who post things the OP wasn't expecting can provide useful insight. The whole reason the OP is posting is because they need advice solving a problem, and maybe they think
that the solution is along the lines of A, but someone else will be like, "Hey, have you ever considered B instead? It's not rude to do B."
To take an example that might be found on this site, a poster might say, "Help! I'm expected to host a big family gathering and there's so many different dietary restrictions and preferences, what are some dishes I can make that meet XYZ requirements?" So some people will post with recipes, but someone else might say, "You know, have you considered going to a restaurant/having it catered/turning it into a potluck? That could make things a lot easier for you." And the OP might say, "Oh, but isn't it rude/tacky to not
cook every single dish myself?" And then people will jump in and say, "No, not at all! As long as you provide plenty of food that your guests can eat, there's no rule that you had to cook it yourself. And if anyone tries to make you feel bad for not cooking, they're
the rude ones."
Sometimes the OP comes in with assumptions that are holding them back, and if they're politely challenged, the OP might see a whole new way of doing things. Of course, the assumptions have to be challenged politely
; and if the OP says, "No, I really, really want
to cook everything myself," other people should respect that and stop suggesting the restaurant etc. as alternatives.