Who would pay attention to ratings from a single unreliable source.
For me the best place are meta sites that gather from many related sizes.
For me the best place are meta sites that gather from many related sizes.
At Rotten Tomatoes they rated Seth Rogen-vehicle "Neighbors" as 100%, last I checked. Meaning only: no reviewer at that point had said it was awful. And yet, I saw it and it was awful.
At IMdB, I can see that it rates as 7.6/10.0, and also that teenager voters loved it (9.0/10.0), where older viewers hated it (5.0/10.0). Far more useful information.
Gunday (the film of the parent article) gets fairer treatment from the IMdB's top 1000 users, who rate it 4.9/10.0
Each site has its own user base, and those users have their own biases. A review from Rotten Tomatoes will vary greatly from those of sites that include only noteworthy critics or only crowdsourced opinion without the "community" aspect. Some communities will be more critical, while some will be less. Like most online reviews, the criteria for rating is completely subjective; one user gives it a 10 because it had their favorite actress in it, while another user gives it a 5 because there was a scene they didn't like. What's awful to you may not be awful to me, and crowd-sourced data or aggregate generalized polling isn't a great way to distinguish that.
In general, I don't trust online reviews for anything because I don't know what 'normal' is or the motivations that people have for voting, as you say here. If I read any restaurant reviews or ratings, it's under the assumption that they're astroturfed.
But, IMdB provides the online reviews I trust the most. I know that the dataset is large enough to be reliable. I feel that people are motivated to vote for their own reference, with minimal outside agenda (this exception is newsworthy because it's rare). As an encyclopedic reference, the site is politically and culturally neutral, compared in particular to national newspaper reviews. I know from experience how the IMdB normally and consistently rates films/genres I might be interested to watch (I know its biases, compared to my own). The stats are openly broken down demographically, with the statistically crucial number of responses, which I feel confident in interpreting. I also know, for example, that new releases will be over-rated according to how close they are to their release date.
By averaging additional information from other sites, I believe it would be difficult to retain those subtle points, which are important to me. I certainly don't believe that Rotten Tomatoes contains the same nuance of information.
IMDb gives a 6.9/10 from 119,115 users. That's the only real statistic it gives us; there is no 'Metascore' for this movie. (Personally I think the Oscar nomination should be mentioned next to this score, but it's sort of buried further down the page)
Rotten Tomatoes, on the other hand, shows us several numbers. The Tomatometer is at 50% for "All Critics", with an average rating of 5.7/10 and 52 reviews. The "Top Critics" Tomatometer is at 36%, with an average rating of 5.9/10 and 14 reviews. The Audience rating, however, is 73%, with an average rating of 3.4/5 from 333,273 users.
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The above example shows how you can sometimes use IMDb's stats of general ratings as a median reference between the audience numbers and critics numbers. But this doesn't always paint the best picture. Let's take another example: the recent (and generally accepted as a flop) 47 Ronin.
Here, IMDb gives us a 6.3/10 rating from 60,849 users. But it also gives a Metascore of 29/100. Yet the number in a gold star in bigger font is just the '6.3'. So even though this movie has a dramatically lower Metascore, they only feature the general user rating from IMDb.
The story is much more dramatic on Rotten Tomatoes. It has a 13% 'All Critics' Tomatometer rating from 72 reviews, with an average rating of 4.1/10. The 'Top Critics' Tomatometer shows 0% with 13 reviews and an average rating of 2.9/10; not one single top critic liked this film, out of 13 critics! Yet the audience rating shows 51% with an average of 3.3/5 with 53,921 ratings.
We can see how IMDb got its '6.3' rating here: both seem to show a middle-of-the-road rating from general audience ratings. But Rotten Tomatoes' critics stats show this movie isn't worth wasting two hours of your life on. The gamble of whether you may like the movie or not becomes more certainly less likely when you take the critics' reviews into consideration.
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As we can see above, even within each website, sometimes they have not only greatly varying statistics, but sometimes missing or hidden information (Robin Hood not having a Metacritic rating and not prominently displaying the oscar nod). People weigh their options based on the data they have at hand, so the information you give people - along with its context - will change their minds greatly, regardless of the source.
This is why I think it's much more realistic to look at multiple different sites. You need as much information as you can get, and no one site gives you all the relevant data, as it varies from film to film and user community to user community. It would seem you can't just depend on 'the crowd' to give someone an accurate idea of whether they will like a film; a survey would probably be better, but nobody's going to survey every film they watch.
If you look below that, you can see the actual "Average Score", which in the case of "Neighbors" is actually lower than IMdB's, at 7.1/10.
The release for that movie is the 9th, so its not out yet outside of limited distribution. Wait until all the reviews come in this weekend for a more complete score.