people get angry all the time at things they have no control over. I recently did over a game, and then i realized i was the only w=one standing in the way of my own happiness.
there are no-no's in every game. they vary from person to person. There is no all guiding rule. You do what you need to do to win(within the rules). There are many rules that groups of people feel apply to certain groups of games though.
freestyle assasin usually leaves you with little room to take other peoples targets without weakening your own position to win; in escalating standard you do not go 20-20 just for a card if you can also get it on a 1 spot. some of these are common sense 9with regards to trying to win the game) but realize this, if we all play by the same guidance, the person to anticipate this will play differently and therefor win... and thats what does count.
above all have fun, and if you do get such a rremark, try to get the wisdom behind it. maybe there is good advice in something, and above all, its your game, so you play it as you feel it must