The thing about writing is that it has no absolute rules (except perhaps, "Keep the reader turning the pages," or in other words, "Don't be boring"), so it's hard to think of any writing advice that's always bad.
I suppose the advice I've seen that's closest to always being bad is "don't post your writing online [or some specific site], because it might get stolen [or the ideas might get stolen]". As long as you pick a site that has some members who know what they're talking about, the benefit you get from having someone read and comment on your work vastly outweigh the minuscule risk of someone copying it and making a fortune from it.
Perhaps I can generalise that into: any advice that assumes a new or young writer is automatically something special is likely to be bad. Of course a lot of them show promise, and you'll always get the lucky geniuses who are publishing in the New Yorker while they're still in diapers, but for most writers, the path to being able to write something worth reading is a long hard slog, and it does nobody any favours to pretend otherwise.