Perfect scores are inherently bogus. If they are to mean a game is absolutely perfect, then the only game that can be perfect would be a Final Fantasy, because it is generally universally accepted that Square games have the best graphics. I have no idea how we're supposed to objectively figure out the best of anything else but a game obviously can't be perfect if it doesn't have the best graphics. So obviously the perfect score really means it's good enough that I think it warrants a perfect score despite its shortcomings. Given this criteria you can give any game a perfect score without any objective justification.
And being a hard reviewer doesn't mean anything either. In case it's not obvious there are very few games I even considered playable these days, so if I was to be a reviewer on a 1-40 scale you'd see very few even breaking a 20. On the other hand I think Fate/Stay Night is a perfect game even if the first 1/3rd is stupid and the last 1/3rd is garbage because the middle 1/3rd is just that good. It doesn't mean anything other than that I really like this game that you've never heard about. I'll go out on a limb and say that IGN or whatever random big US gaming magazine is probably as respected here relative to Famitsu in Japan and yet if they give a review you don't agree here in the US people are quick to say they are wrong or they suck.
Reviewing hard all too often just gets you into the trap of "I like this game and because no one else has ever played it it must mean I'm right because everyone else is too dumb." And I mean that in a relative sense. For example most people who have a DC probably did play Soul Calibur 1 even if the gaming populace on a whole did not, and Fate is the best selling Japanese computer game ever. Vagrant Story comes to mind as a good example of that, which is convenient since it got a 40 from Famitsu. For all its romantic dialogue and kind-of-cool gameplay, there's a very good reason why it didn't sell all that well (game was way too long for the amount of story it had). Now obviously the guys at Famitsu decided that putting a plot fit for a 6 hour game and stretch it to 20-30 wasn't bad enough to not give it a perfect score, but like I said before, there's no particular reason why they're right or wrong on this and certainly a lot of peopel do disagree as reflected by the sales.
And I guess in that sense, the perfect game has to be one that sells a lot, at least relative to the market it's in (for example, Soul Calibur). I've been thinking this for a while. A lot of people who played Terranigma think it's like the best action RPG that ever existed (including me), but if it's so good, why is it that Chrono Trigger is the game that racked up the sales even in Japan (CT is RPG, but the style of the two games are close enough to make the comparison IMO)? And if sales is an indiactor of quality, does that mean reviews only exists to reassure us that we're not really wrong for liking a game that nobody (relatively) bought?