They could be shot as intentional fouls.
That whole "intentional foul" stuff is shady, as far as the line between sportsmanlike and unsportsmanlike conduct goes.
For instance, intentionally fouling to tie a ball up or put your opponent in trouble is "acceptable", as long as you do it by striking the cb first. I believe it would be considered unsportsmanlike to actually move a ball without striking the cb first. Other than that, I'm not sure what constitutes unsportsmanlike conduct with some intentional fouls.
For instance, not even making an attempt to strike the cb is "acceptable" when playing 1-pocket, which to me is unsportsmanlike. I'm talking about when a player simply taps the top of the cb with his tip and says "I owe one". But that's where the 3-foul rule can be helpful... do the same thing right back, and if he does it again, tell him he's on 2 fouls and then you do it again. If he does it a 3rd time he loses the game.