I call bullshit on this statement.
You can make builds that are absolutely indestructible/unstoppable or deliver your character's dialogue with faultless accent and idiosyncracies, but if at any point you are the reason other players and/or the GM didn't have a good night of gaming, then you're a BAD player.
This is because more often than not, when the players have a bad night, the GM tends to take the fall - failing that, the C.O. player is next in line. Only AFTER those two steps are gone does anyone else get the blame. If the goal of the game is for everyone to have fun, it falls to the GM to make sure the underoptimized also have fun, not the C.O. player.
I am not one who likes to adjust playstyle to the table at hand. I know the rules, I know what I can do with them. I don't go out of my way to break the game, however.
Maybe I didn't structure my statement well or you didn't read it right, but at no point was I talking about blame.
I'm talking about being an ass, which you address in the last part of your post (Where you say you don't go out of the way to break the game).
In my groups players don't lynch the GM when it wasn't a great night and they don't hate on the C.O. player either. So blame isn't a factor at all for me. People I play with are mostly pretty reasonable. It's not my good luck that makes this so, it's my good judgement. I've walked away from more games and/or groups than I've stuck with, because I know better than to play with people when there's no chemistry between us.
As for it being the GM's job to babysit the unoptimized, I know what you mean, but I disagree somewhat. If I'm capable, I as a player do my best to help everyone out and get everyone optimized. The people who don't accept help from anyone usually learn their lesson, because like I said, I play with reasonable people. I even had one guy say "My characters may not be GOOD, but..." which was enough to tell me that he was comfortable being mathematically unreliable. That's fine. Now when I hear he's making a rogue or cleric, I know that the rogue or cleric role has not and will not be filled by his character, so I need to account for it elsewhere. He still has a good time playing his pure RP characters, and the rest of us pick up the slack.
Now when a character becomes a genuine burden or hindrance to the group, it's a different ball-game. A waste of space is not so bad as a ball and chain. Usually I find these easier to deal with since the problem is obvious and it's not hard to get back up. Everyone is different though, so I don't have any catch-all suggestions there.