The cloth resting point? You mean the point where the invisible ghost ball would rest on the cloth if it were an actual real physical object?
You think that this is SO EASY.
Well here is an experiment you can do. And let's use GMT's premise that being off by a human hair's width will result in a failed shot - (unless subconsciously adjusted for) -
Take a piece of paper, a ball, and a fine tip sharpie.
Put a dot anywhere on the paper. Put the ball on that dot. now take your sharpie an put dots all around the ball at what you think is the Ghost Ball center.
Should be an easy exercise since you are sitting at your desk, with all the time in the world, not standing above the table with a cue stick in your hand under pressure to shoot.
When you are done pick up the ball and measure the distance from the original dot to the estimated dots and see how well you were able to measure JUST the distance alone. This doesn't even take into account being able to accurately place the invisible ball along the right line which SOME people can't consistently do with a REAL ball.
Here a video of me trying this experiment ONCE and only once. Using the same measuring tool that would be available to me if I were at the table, my brain. Watch it and see how I did. I bet none of you who claim Ghost Ball as the greatest way to aim will even try it and put up your results.
http://www.youtube.com/watch?v=d-L4QMNiVxk
Only 3 of the 11 dots were even within .15" (that's a fifteenth of an inch) of 2.25" from the center of the object ball. The rest were off by an average of a quarter inch.
Let's see how well you can do it.
And by the way Dave. I make your three shots with no adjustment in alignment, bridge length, or pivot using CTE. Just like with GHOST BALL I don't figure the angles or the offsets. I look, bend down, pivot, and shoot.