The Five qualities of a Good Gamer are:
1. Good Manners
Good manners is a top quality of any human being. My definition of good manners is similar to that of Miss Manners' - the quality of taking care not to cause other people undue offense. This includes many things:
* Listening as much as talking, because other people have egos as big as yours
* Taking care to observe local customs
* Acting in a manner that increases everyone's enjoyment each session
* Keeping yourself and your surroundings clean and well-kept
* Good sportsmanship as both winner and loser
and many other items too numerous to mention.
You really can't be a Good Gamer without some modicum of "gaming intelligence" (I will qualify intelligence here as "gaming intelligence", because some otherwise very smart people in other areas just aren't going to shine when it comes to games). Time spent with them may still be very enjoyable, the friendship may still be valuable, and no judgement would ever be cast on their worthiness; but it's not really gaming. Maybe it's socializing.
Most people have difficulty grasping some rules and some games; this doesn't mean that they are not intelligent or "gaming intelligent". After a few attempts, they can pick it up. If they can't, then after a point you realize that you are never going to be challenged playing a game (or this game) with them.
This could be a sub-quality of good manners, but even a well mannered person may gracefully give up too quickly. To learn some games (and actually hear and understand the rules as they are explained), to become good at them, and to be respectful when others take time to make a difficult move, requires patience.
Curiosity is what is going to get you playing to begin with, keep you playing, get you to try out new moves, break out of group think, and get you to try new games.
Similarly, you need creativity to try out new moves (curiosity to want to find new moves, creativity to actually come up with them) and to make the leap into a game's "system of thought". Creativity also allows gives you license to look at games and game systems and dream up something better - tweaks, variants, new ways to harness the fun beyond what comes in the box.