As you know, it is all a matter of opinion. You kinda have to feel out the writer. If that person is complaining about everything and rates a place a 1, take it with a grain of salt. They might have been having a bad day and they rated the campground on one experience. Read into the reviews. That 1 would probably be a 4-6 with 3 or 4 different campers and it might be a 9-10 with 1 or 2 campers.
Now the way I look at this is: You probably would not get a 1 or a 10 out of me. I would start off at 5 or 6 and go up or down from there. I just reviewed Aces High and I gave it a 7. It was a nice park and I really didn't have any complaints about it (with the exception of it being high priced in the off season). My highest rating would be a 9. I know there are alot more campgrounds that are nicer, cheaper, cleaner Friendlier, etc... which would get rated an 8 and if it was perfect, I would give it a 9.
On the other side of the scale, 5 would be staring off and if it was the absoulute worse place I have been to and I have complaints and all, I would give it a 2. If it was a little bad, I would rate it down to a 4 or 3 if I had more problems with it.
One solution would be for the reviewer's member number or something to appear with the review. That way if for example I rated 5 or 6 parks an 8 and you stayed at a couple of the parks, you would get a feel for how member # ??? critiques. If you feel that the parks were only a 4 in you eyes, you would be able to see mbr # ??? rated this park an 8 and you would know what to expect when you got there (or you might decide not to go there). As I said, it is each persons opinion and what is good for one person (for example children or pets) might not be good for someone else.
There was a previous post about this. I can't remember exactly when it was, but I just joined a few weeks ago and I read most all the previous posts before I joined. Take care and happy camping!