Your reputation doesn't matter. Once the rules are changed, you are on a slippery slope of changing rules. The game slowly ceases to be poker. When I am playing chess, I demand that the white moves first. When I find myself as the black, knowing that the opponent had whites the last game and it is now my turn to make the first move, I rather change places or rotate the chessboard than play the first move with the blacks, although it would not change my chances of winning. (I don't remember the standard openings, so I wouldn't be confused by the change of colors. And even if I were, this would be the same for the opponent.) Rules are rules in order to be respected. They are often a lot arbitrary, but you shouldn't change any arbitrary rule during the game without prior consent of the others, even if it provably has no effect to the winning odds. I think this is a fairly useful heuristic. Usually, when a player tries to change the rules, he has some reason, and usually, the reason is to increase his own chances of winning. Even if you opponent doesn't see any profit which you can get from changing the rules, he may suppose that there is one. Maybe you remember somehow that there are better or worse cards in the middle of the pack. Or you are trying to test their attention. Or you want to make more important changes of rules later, and wanted to have a precedent for doing that. These possibilities are quite realistic in gambling, and therefore is is considered a bad manner to change the rules in any way during the game.

When you deal Texas Hold'em, do you "burn" cards in the traditional way? Neither I nor most of my friends think that those cards are special, but it's part of the rules of the game. Altering them, even without [suspicion of] malicious intent breaks a ritual associated with the game. While in this instance, the ritual doesn't protect the integrity of the game, rituals can be very important in getting into and enjoying activities. Humans are badly wired, and Less Wrong readers work hard to control our irrationalities. One arena in which I see less need for that is when our superstitious and pattern-seeking behaviors let us enjoy things more. I have a ritual for making coffee. I enjoy coffee without it, but I can reach a near-euphoric state with it. Faulty wiring, but I see no harm in taking advantage of it.