Thanks for sharing that Skalchemist!
7/10 games being good is awesome, and I am glad that has been your convention experience! Mine has not been so fortunate, but my sample size might also be small compared to many die hards. We're talking like 10 Marcons, 5 Cincicons, 12 Origins, 6 Gencons, ish. Mine has been about 50/50 on good or decent vs. bad.
I personally differentiate bad game from bad GM though. A bad game is one that was either not prepared well, written badly, or where the GM didn't know the rules very well.
A bad GM to me only has one definition, and that is someone who is some combination of antagonistic, unfair, punitive for you playing/character building what they consider "wrong", or ones that want to "teach you a lesson". I have run into a LOT of teach you a lesson sorts at cons. It was happening frequently enough that I finally just quite going to them - why pay for that experience when I get the fun version with home games and Missions game days for free?
Edit: How do you find the quality and attitude of gamers in Canada vs. the states?