I would say that being really intelligent (how we choose to define intelligence also really matters) does help in terms of efficiency in getting to the top, but being determined enough to put in the time necessary to get to the upper echelon of pool players trumps intelligence by far. You can...
Yes, there are always multiple reasons that are more realistic that can cause a pro to miss a shot, starting with the most common; their focus dipped even just slightly in that fraction of time. Pros are mere mortals just like the rest of us and will make mistakes too.
One of the biggest contributors to me missing early on was bad aiming and mainly caused by not properly lining up my shot when standing up and trying to aim after getting down on the ball. For the misses on crucial shots, it was pressure causing a lack of proper focus.
A glove should always be recommended no matter what. Without a glove, the shaft gets dirty and sticky from natural body oils and thus introduces more variable to your stroke. If you can avoid that for something that costs $20, why wouldn't you?
Some additional ones I recalled watching a buddy play...
Focusing too much about where the CB should/would go
Standing up right after shooting to try and follow the shot
Thinking that hitting hard makes you more accurate
Not chalking after every shot (unless you use Taom chalk :cool:)
Wow... the last couple of pages have really derailed this thread into "ignore" territory.
Also, after getting my Mezz back from Proficient Billiards, I have re-confirmed that my best personal cue to date is STILL the Mezz cue with an Ignite shaft.