I once read in a pool book (byrnes i think) about the diamond system and 14.1 position play, and in that book there is one shot every pool player need to master. In that particular shot you place the CB in the center of the table. Aim at the 7th diamond - diamond between right corner and middle pocket. You apply some left spin. The CB travels then from the middle, to the 7th diamond, til the 2nd diamond on the short rail, then to the another 7th diamond on the other rail and last back to the center (2-7-2 system may be the name of it). If applied correctly, the ball should end up on the exact same spot you start (but probably near it). And when I do this I get the speed of the table, the spin of the rails and a general feel of the table. No need of pocketing balls. My eyes would tell me if the pockets are tight, tough, easy to cheat, or whatever. But hey, I am only 18 years old and I don't compete in pool on a regular basis, but I do shoot 50+ in Straight Pool and I believe this is the one and only best way to get a correct impression of a table when you only have one shot to try.
In addition, this is my first post here, so hello guys. And sorry if my english ain't the greatest sometimes.
/N