In my experience, unpleasantness at the board is quite rare, and in general I find that the stronger the players, the less trouble there is.
As already pointed out, this is the main reference point:
FIDE LAW 12.6 "It is forbidden to distract or annoy the opponent in any manner whatsoever. This includes unreasonable claims, unreasonable offers of a draw or the introduction of a source of noise into the playing area."
Drinking non-alcoholic drinks at the board is reasonable, as is eating snacks such as biscuits or chocolate. Eating anything noisy, smelly or visually repulsive is out of order.
For instance, during a long game I will sometimes eat a banana - since bananas are quite smelly, I take care to eat them well away from the board.
If there is an arbiter present, any complaint should be made via the arbiter. For an example of how not to do it, see
http://www.chesscafe.com/text/davies62.pdf In a team match, in the absence of an independent arbiter, it is the duty of the team captains to try to ensure that the Laws of Chess are upheld. My local league has this rule:
"Team captains are joint arbiters and have all the duties and responsibilities of arbiters under the Laws, unless those duties and responsibilities clash with their role as team captain."