Few people even consider room conditions. One of the tricks of the trade and one a traveling man learns. I have mentioned many times the lighting in the closest bar to my house. Unusually strong sidelight made the balls seem maybe a sixty-fourth or less over from where they really were. People didn't notice on most shots, it would bite somebody in the ass when they needed a tough shot perfect for all the marbles. Not something I mentioned to many, I had to learn so did they!
Another hall had the main table by an unshielded picture window. For about forty-five minutes a safety was anywhere along one long rail. Bend over without squinting your eyes to slits first and your eyes were toast for a game or two. It was a safety++ to trick somebody into looking into the sun eyes wide open. Another place, climate control blowing on just one side of a table was murder on an unsuspecting banks or one pocket player in particular. One half of the table had soft cushions, the other side they were like bricks!
There was an old time road man that would sneak his personal set of balls into big matches. He would sometimes refuse a tough match if he couldn't get at least his cue ball into the game.
Shots down the rail, touching or not, became almost unmissable when I quit shooting at the front corner of the pocket and started shooting at the middle of the back pocket wall I could see clearly. I first learned to move out a little when the old ten footers with unequal pockets would bounce out into the table when rolling past a side pocket tight on a rail. It was one of my checks for years to see if balls went past the side pockets cleanly or not.
If one player reads the table and the room, often the cue ball too, and the other doesn't, the careful player will win some games just by observation. If you are really a cold hearted bastard you can bait people into taking these bad shots, not that I personally ever did such a thing!grin)
Hu