"People who bash (paid or not) don't have the same requirement as far as I know."
Well, I could be wrong as I've never seen a documented case, but the way 17b reads, I believe, is that if you're compensated to discuss a stock (layman's terms) then you must disclose. I've always taken that to mean positive or negative.
But, again, never have I seen a case from the SEC or any actual "proof" of anyone being compensated to bash a stock.