My prescription is sunshine. 
When I look at public forums in general, I do see some folks using them for gorilla marketing (haven’t seen much here). I do like the idea of forums with rules that require that signature lines require folks with business relationships to products disclose the relationships.
Other than that, I think the majority of posters are simply sharing the best they have to offer with others about a hobby they enjoy. The best cure for bad advice is good advice. Steel sharpens steel. Rather than admonishing posters about how to advise others, simply providing another viewpoint to the thread adds the requisite sunshine. Readers quickly learn from posting history how to weigh individual posters advice.
I love it when I see posts like: “That might work well in sandy soils, but with my heavy clay, I find that…” or “That may work well in your zone, but here in zone 5, the growing season is too short to…”.
As long as the critique focuses on the topic and not individuals, it benefits all of us as we share from various experience levels to form a community.