The WPA rules include a listing of items that are considered unsportsmanlike, but those are just examples and not a complete list. For example, they do not include damaging the equipment. You can find the rules at
http://wpapool.com
Be sure to look over the regulations there as well as they describe how the rules are implemented and some related matters.
Another good source of rules with explanations of rulings is on the CSI/BCAPL website. They were based on the WPA World Standardized Rules.
My column in the August issue of Billiards Digest is all about unsportsmanlike conduct.
Note that both the Rules and the Regulations talk about referee discretion when it comes to unsportsmanlike conduct.
The Rules say: "The normal penalty for unsportsmanlike conduct is the same as for a serious foul, but the referee may impose a penalty depending on his judgment of the conduct. Among other penalties possible are a warning; a standard-foul penalty, which will count as part of a threefoul sequence if applicable; a serious-foul penalty; loss of a rack, set or match; ejection from the competition possibly with forfeiture of all prizes, trophies and standings points."
The Regulations say: "The rules and regulations give the referee and other officials considerable latitude in penalizing unsportsmanlike conduct. Several factors should be considered in such decisions, including previous conduct, previous warnings, how serious the offense is, and information that the players may have been given at the Players’ Meeting at the start of the tournament. In addition, the level of competition may be considered since players at the top levels can be expected to be fully familiar with the rules and regulations, while relative beginners may be unfamiliar with how the rules are normally applied."
All this is well and good, but when there is no referee, the matter of resolving the penalty question might become quite a bit more difficult.
Take, for example, the common case of a player in a straight pool match who, unfortunately for him, has sent the cue ball directly toward a pocket mouth. In this hypothetical, he decides to catch the ball with his hand before it drops, or to block it with his cue stick tip before it drops. Should there be any penalty, other than the one that would have ensued had he simply let the cue ball drop?
Among the examples of unsportsmanlike conduct cited by the Rules is this one: "using equipment inappropriately." The Rules also say: "It is a foul to touch, move or change the path of the cue ball except when it is in hand or by the normal tip-to-ball forward stroke contact of a shot. The shooter is responsible for the equipment he controls at the table . . .. If such a foul is accidental, it is a standard foul, but if it is intentional, it is 6.17 Unsportsmanlike Conduct."
For a real world example of a player blocking the cue ball from entering a pocket (and causing it to go off the table!), see this match between Corey Dueul and Mike Dechaine (which includes other "goings on" and is quite entertaining):
https://youtu.be/XqDVtRcZiSY. It appears that those two players decided, without discussion, that the penalty for the intentional foul committed by Corey, which by Rule was unsportsmanlike conduct, should be nothing beyond the one stroke penalty that would have been earned had Corey simply allowed the cue ball to drop into the side pocket.