I typically say gg whether I win or lose.
Same. I started saying it because I thought that it was always the polite thing to do, as in "show you're not a sore loser by saying gg", or say gg when you win just to show your opponent that you're trying to be a good sport about it and not rub it in that you won 85 to 30 or something like that. I mean, which is better: saying "hahaha you suck! Look at me I won by 55 points!" or just saying "Good game!"?
As an aside, in principle I do agree with that running up the score as high as you can just to run up the score as high as you can is a jerkish thing to do, but I do have two exceptions to that rule:
1. Games with Kingdoms that warrant the building of a well-oiled Goons Engine, these games can also (but don't have to) involve Dominate. I mean, in these types of scenarios, when one player gets going, it's almost impossible for that player
not to run up the score, as far as I know.
2. Games with my Brother (he generally runs up the score on me when he can, especially if we're playing online, so it's only fair for me to do it back to him when I can, although these days one of us usually just resigns when it's clear that the other one has pulled together a game-winning engine
)
Note: Exception 2 usually happens in Goons games, with Dominate (but not always with Dominate)
EDITS: Additional wording and phrasing added in for additional clarification