(inspired by derail of
http://forumserver.twoplustwo.com/sh...8&postcount=29)
Seat changing, table changing, talking about how good/bad a game or player was/is at the table. Someone asks you what you had and you stare at them stone faced. A recreational player flashes his hand to his neighbor before he folds and someone tells the dealer to show the whole table.
Everything above is theoretically +ev. In aggregate they send the message that poker is about winning money more than it is a game. This encourages people who play poker for fun to either treat poker like it is about winning money, or go find a more relaxed environment to play in.
When you sit down at a poker table, are you a competitor or are you the casino? Are the other people at the table your opponents or are they your customers?
Honest question that you should think about and decide on. If they are your opponents, hide information/try to get extra information, sit on their left, do whatever you need to win money from them. But know that it is very difficult to make a lot of money from your opponents, because they are playing the same game as you.
If the other players at the table are your customers, be nice to them. If they ask, show them your hand. If a bad customer (aka a regular) is berating a good customer, step in
respectfully. Do NOT give the impression that your business is about twisting every last penny out of them and they are more likely to come back.
tl;dr: table changing and seat changing are +ev in isolation and -ev in aggregate. If you are playing poker to compete, go for it. If you are playing poker to make money, treat the other people at your table like they are your customers, not seats to drain money from.