I wouldn’t worry about it at all. If you feel like vitriol, post that too.
Honestly, I don’t see why people are supposed to couch their feelings in soft, fuzzy, sugary language, or why there should be any “guidelines” at all in how to express displeasure.
If you think a wine is crap, state as much. You don’t have to say you found it “challenging” or “difficult” or “not your style” or any of those other things. If you drink a wine and think it’s sour, thin, weedy shit, why not say so? And if you think it’s generic, sweet, gooey and nauseating, why not say so?
So what if it’s a “board favorite”? What is that supposed to mean anyway? That a dozen people post enthusiastically and frequently about it, perhaps hoping to get a few samples or be treated nicely if they visit or just to be considered in the mix? Or because they truly like it?
All of those are likely and all will mean that they disagree with your view and what is the problem with that?
This is all just imaginary anyway - it’s one opinion vs another. There’s no blood on the ground. If you take a machete and physically attack the wine maker, that’s obviously a different order of business, but stating that you can’t stand a wine, no matter how vociferously, is not going to stop the earth from spinning.
And if you’re not attacking the wine maker as a person, you’re just attacking the product, what’s the harm?
Moreover, does anyone think that other people won’t write and say worse things about a wine? I watched a guy take a glass of a fine Mascarello from Maria Teresa, sip it, and exclaim that it’s shit. She told me it wasn’t the first time she’d heard that - some people just don’t like her wine.
And as others have mentioned, expect to get hit back. Don’t be like some thin-skinned critics who dish it out all over but are offended when it comes their way.
BTW - everyone is wondering exactly what that wine was!