As I may have mentioned before, I began playing online on a membership site. It was considered to be a community for learning poker players, much like this. For the most part it was a pretty friendly, polite atmosphere to play poker in. But I learned early on, when I jumped out of my seat at the end of hand to run downstairs and check on my sleeping grandson, that one of the rudest things you could do is not acknowledge another player's "nice hand".
There were apologies all around once I explained that I was away from my computer momentarily. That is, I apologized to the girl who had offered the "nice hand". All the others who decided to weigh in subject could kiss my ass. Besides the fact that it wasn't any their business, I really hadn't been away from the table long enough for there to be so much hubbub. In fact if hadn't been for half the players at the table and a few observers commenting, I might have come back and seen the "nice hand" in the chat box and given a reply.
At any rate, since then I always respond to "nice hand" with my standard reply of "preciate it". Sometimes I think the "nice hand" might have been meant sarcastically. It doesn't matter though, since half the time it's coming from players that are so bad, I wonder if they would recognize what a good hand is.