Newbie PSA ticket grading questions

[nolemmings]

I am pondering whether to get into collecting tickets-full and stubs--and would appreciate some basic info on how they are graded. I see some stubs graded authentic while others receive grades with appearances that seem indistinguishable to me. What are they looking at/for? I have seen stubs parted cleanly at the perforation given the "A" while others with uneven edges--either tears inward or surplusage beyond the perforation receiving numbers. Is there at least some logic and consistency that escapes me?

I see from PSA's website that submitters can request a non-numeric, "A" grade for stubs, but did not see that option for full tickets. What advantages are there to foregoing a number? Why would a full ticket receive an authentic grade?--seems even staple holes or writing would make it a poor 1 and not just authentic.

Third,what is the ticket collecting hobby's view of PSA or any other TPG when it comes to grading tickets? I am no fan of the company, and at this point would use them merely to guaranty authenticity. Does their involvement noticeably increase value, and are there significant jumps in price/value between one number and the next?

Finally, what is the value drop-off from a ticket stub that receives a numeric grade to one that is slabbed as "Authentic". I have seen a few World Series stubs marked "A" that look to be nicer than their numeric counterparts-- 1968 comes to mind.

Any help appreciated.