Yeah that's part of the reason I usually don't say much or anything after a match with somebody I don't 'know'. I've got some crazy responses just from saying "gg".
Very recently (like a week ago) I played some guy in Rockstar Table Tennis and we had what I thought was a pretty close, tense, fun match. I won and I sent him a "gg!!" and he said "YEAH WHATEVER YOU GOT LUCKY". It instantly ruined the match we just had.