Ahhh... so perhaps part of a person's grading perception (whether they think grading is tight or loose) is that individual's grading frame of reference. So my Über-simplistic, hyperbolic example would be every book I send CGC is, I believe, Gem Mint but they keep coming back much lower than that. So CGC must be grading tight. Whereas your tight- grading thinks every book is a 1.0 and they come back much higher than that. So CGC must be grading loose. Frame of reference...
Quod erat demonstrandum. Pretentious mic drop.