I think people expect way too much out of the individuals reviewing games. Just review the game based on whatever criteria you feel necessary an let the people reading your reviews judge if they give two shits about your opinion.
Face it - someone doing a review has to look at the genre of the game, the controls of the game, the artistic merit of the game (graphics, audio and story telling) - then, they have to compare how they perceive all of this to how they've perceived other games in the past.
Since we've all likely played different games - on different platforms - at various points in time - and at various skill levels - with different preferences, we're all going to have different opinions on what makes a game fun or not.
Take Halbred's review of Birds and Beans, for example. This is a simple, $2 game - ideally there shouldn't be much to debate on it. However, he, apparently, disliked it greatly. "I have buyer's remorse over a free game, so that should tell you something."
Five replies down, someone says "Funny enough this was a "killer app" for me."
So, we go from "I feel bad I wasted the money Nintendo gave me" to "I bought a $170 system for this game" - all over a $2 game.
Those of us (I'm assuming rbtr based on his mini-review of the title and myself) who were raised on arcade-like shooters can appreciate the quality put into this title and would recommend it - I'd say it's worth the $2 easily. $5 even. However, it seems to me that Halbred likely wasn't raised with the Arcade-Space-Shooting Genre - a type of game play that's so simple and repetitive that it's easy to understand why so many people can't stand to play one for more than a few minutes.
All of this analyzing over a $2 game. And you want to establish a guide for a "fair" review of $50, multi-million dollar development titles?