My biggest pet peeve in pool is the number of excuses about losing because of bad luck. Unless you played a perfect set with 0 mistakes (impossible) and your opponent slopped in the 9 hill hill you really have no reason to complain about bad luck. In all honesty you made mistakes earlier in the set that cost you the match, not your opponents lucky rolls. I try to simply focus on what I could have done better, anything else is counterproductive IMO.