Subreddits that are about buying things (/r/buyitforlife, /r/frugalmalefashion) are done. Same with any askreddit thread that's like "What's a product for under $x that changed your life" or something like that.

I still find /r/cooking gives good recommendations, despite the fact that the world of recipes is filled with spam and low quality content. Maybe the unit economics of astroturfing just don't work out for it.