Sure, but presumably you hone your senses as to which subs are trustworthy and which are not. For many classes of queries, there are some well-established subs already. Then it is a simple matter of parsing the comments, and the signal-to-noise ratio tends to be fairly decent for lots of things still.
Thats not really the issue, its obvious these crap sites are crap, the problem is them polluting google results.
They are. If you look at /r/suggestalaptop they already have people who suggesting laptops and link with Amazon referral links. I'm half convinced that they are just bots.
Most subs ban Amazon referral links for this reason.