Well first of all Capcom can't lie about their sales, that would probably be against the law. They already have the actual sales listed on there investor site so there's no way they can lie, and if they did lie they would probably put higher numbers then what there actual projection called for.
Also, you also bring up a good point. If Capcom is lying and if reviewers are getting paid by Capcom to give DmC good scores...then shouldn't we question all the games in the past that have received good scores? Ya know, like DMC 1 and DMC 3? They obviously must be paid off right? Because DMC 3 can't be a score of 9 game, right?
I mean the average DmC score i've seen in various sites are around an 8 and a 4 stars out of 5, this isn't exactly the score i would pay top dollar for if i was Capcom if that's the best they can come up with.
Anyway, like you said, people can't simply pick and choose ones that are convenient for them.
There has been many indications that sites take payments indirectly.
It's not Black and White, there are many different scenarios.
Sometimes a reviewer gives a game a bad or good score out of simple bias
Sometimes a reviewer gives a game a good score out of corporate bias i.e they have been bribed
Sometimes a reviewer gives a game a good/soft score out of bias leaking into them by having a good relation with a game company
e.g Angry Joe: i am not saying he's bribed but i feel he is in "happyland" when it comes to Witcher company. Because they have been kind to him.
Agngry Joe goes to Witcher studio
That fun experience could make Joe be biased when reviewing a witcher game. Perhaps the Witcher game is not that good, but Joe will still at end of video say "It's worth a buy" when in reality it's not.
Sometimes a reviewer gives a game a good or bad score based on their user experience
This is bad because if you don't like RPGs, and your job is to review a RPG, then you will slam a 8/10 because you thought "I didn't have fun" i.e it wasn't your taste.
A example of this could be
God Hand IGN, they gave it 3/10, and i hear the game is pretty fun brawler. So why 3/10? Surely such game deserves at least 6/10 lol
Sometimes a reviewer gives a game a good or bad score because they are being ethnocentric
Sometimes a reviewer gives a game a good or bad score because they don't know better
And on top of all that, these professional reviewers are getting paid for their job, so they may give a game a lazy review and not a indepth one because they must meet a deadline.
Professional btw is another word for "I get paid to do this", it does not mean they are good at their job.