All right where do I start. First of all how did "english" all of a sudden become "spin?"

We never called the use of english on the cue ball spin, NEVER! If we used outside english we might call it "throw" and inside english was just called "inside."
Okay, I got that out of the way. Secondly, it's very hard to hit dead center on the cue ball and only a few ever mastered that art, Buddy Hall being one of them. Buddy used center ball like a kill shot that would slowly roll forward after contact with the object ball. When he hit the cue ball with center ball it made a different and distinctive sound. It sounded like the cleanest of clean hits on the cue ball and very few others could duplicate that. That said, Buddy and all real pool players rarely try to hit center ball, using some degree of english on most every shot, whether it be high, low, left or right, or some variation of these, like high-left or low-right. I have to say it kind of bugs me when someone talks about using one tip inside english or a tip and half right or left english. I don't think the use of english can be categorized that finitely. A good player does not think about (and aim for) exactly one tip right, left or any other way. They are actually feeling the amount of english they need to execute the shot and it can't be described terms of one tip, two tips or any fraction in between. Instead it is a point on the cue ball where the player feels he needs to hit it (and at what speed) to move the cue ball to the next desired location. On one shot that may look like he's aiming slighty to the right of the vertical axis and also a little above the horizontal axis. And on another shot it will look completely different. Try discussing that point of aim using one tip this or that. You can't! That my friends is how english is applied to the cue ball by just about every player you are watching in these tournaments.
Okay I'll take a break now and see what comes up.