I run a closed PUG group that has some outliers but targets the NC/AM/IM demographic. Based on my experience running and player feedback, I think some qualities of a good PUG server are:
- Gatekeeping: I decide who gets in, and I do my best to make sure that new additions aren't bigoted in or out of the server
- Heavy moderation: I talk to people privately if they behave poorly, (snide remarks, bullying noobs, malding, etc) and remove if there's no attempt to improve. Bigotry is addressed publicly to assure players that it isn't tolerated and will be dealt with appropriately (doubles as a teachable moment; personal growth > punishment if possible)
- Emphasis on sportsmanship, patience + teaching with newer players, and encouragement/runner assistance with drafting even teams
I think my time and energy for this kind of moderation is higher than most, so I don't necessarily expect it from other PUG servers, but the result is a chill server with a community that cares about itself and fosters friendships. It's really rewarding when more casual players demonstrably improve in 6v6 through the group or make connections and join teams, too.
tl;dr I like when I don't have to worry about someone running permajumper, screaming on mic, being exhaustingly passive aggressive, or saying slurs.