So because I haven't got much better to do on a friday night, I decided to take the score list from that magazine scan, plug it into a spreadsheet, and see if I could find anything interesting. Like maybe bias. One of these days I'd like to compare these scores to square inches of ad space, and see if there's a corelation. I can't do that yet, but I did find something weird.
The average score of games, by platform, was:
(reviewer) Steve Harris; Ed Semard; Martin Alessi; "Sushi X"; EGM overall
NES 6.2352941176*; 6.2352941176*; 5.9803921569; 6.2254901961; 6.1691176471;
SMS 5.35; 6.1; 6; 5.7; 5.7875;
SNES 7; 7.0833333333; 7.25 6.8333333333; 7.0416666667;
Genesis 6.5652173913; 6.9347826087; 6.5869565217; 6.8695652174; 6.7391304348;
TG16 6.3636363636; 6.4242424242*; 6.4545454545*; 6.4545454545*; 6.4242424242*;
GB 7.64*; 7.56; 7.64*; 7.88; 7.68;
LYNX 6.6363636364; 6.3636363636; 6.8181818182; 6.2727272727; 6.5227272727;
All systems (by system) 6.4650852515; 6.6029925857; 6.5800126586; 6.5670546901; 6.5537862965;
All systems (by game) 6.437751004; 6.5582329317; 6.421686747; 6.5301204819; 6.4869477912;
Note the numbers with asterisks. Maybe I don't know enough about statistics, but it seems unlikely to me that, across a platform, two reviewers would have the exact same average between them coincidentally. Also note that this happens twice to the TG16: the average of Semard and EGM overall are identical when it comes to the TG16.
Hastily drawn conclusions: EGM as a whole disfavored the NES, SMS, and TG16(by -0.3178301441,-0.6994477912, and -0.0627053669 points, respectively) and favored the rest, especially the Gameboy(+1.1930522088 above average; everything else was favored by a fraction of a point.)
As for individual reviewers: Martin Alessi favored the TG16, while the rest disfavored it; He was also the biggest Snerd. Steve Harris HATED the SMS (disfavoring it by more than a whole point); "Sushi X" was the hardest reveiwer to please, unless he was playing a Gameboy(favoring it by 1.3498795181 points; the next most favored was the Genesis at 0.3394447355); Besides the TG16, the only system where some favored and others disfavored was the Lynx(Semard and "X" disfavored it, the others favored it).