Depends on the arena. If we rip a course on this site, nobody cares. Negative reviews are often unseen.
GD or GW does not have an article or column for "Worst New"
How many "poor" reviews have you ever seen and where have you seen them?
My guess is that they are in VERY VERY VERY narrowly-focused arenas. If you hear of a course through anything other than word of mouth or a forum-setting, chances are it's because it's generally liked for one or more reasons.
Would the golfing world at large know about Tierra Rejada or Eagle Glen? Doubt it. Those are two poor courses in the LA area that charge near 100 bucks a round. Likewise, I haven't heard of any poor courses in the East anywhere but on this site or through word of mouth.
I do, however, hear about the small modest clubs that get national recognition in the travel pages of GD, or in the Best New or Top 100 Affordable rankings.
Seems to me that reviews are only seen on a transcendent level when they are positive, or at least espouse a virtue of the course. If the course sucks, it doesn't make it to print.
Yes, a bad review would murder a course. Thing is, there just aren't bad reviews that are visible enough to matter. At a local level, negative word of mouth is the worst review you can get.