Does PSA grade trimmed cards?  Based upon the number of returns when I search the Web for an answer, “Yes!” 

"1963 Topps Willie Stargell RC PSA 6 CENTERED"

Maybe I should have known better based upon the eBay listing shown above that bragged about centering for a card known for being off-centerd.  I purchased a Brock Davis/Willie Stargell rookie card off eBay from a seller with excellent feedback.  When it arrived, the card rattled around in the plastic holder.  I emailed the seller, who was adamant that the card was not trimmed—and that PSA would never grade a trimmed card.  So I emailed PSA, which replied they do not grade trimmed cards--all togeher now, "Duh."   Next I compared the card to all my other graded cards and confirmed that this card was clearly smaller than all of them.  None of the others moved around from side-to-side, top-to-bottom, like this one.  The other suspicious characteristic was that the card really was well centered as advertized—a rare find among these cards. 

So what did I learn?  PSA’s grading standards vary surprisingly widely from card to card, but this clearly trimmed card was so extremely small as to raise serious concerns about PSA’s quality control and the trustworthiness of the seller.  My conclusion was that any experienced seller taking a professional’s due diligence in handling a valuable card would have known this card was trimmed to appear more centered than it was when originally printed.  I was fairly new to collecting graded cards, and it took me two seconds to know the card was bogus when I first held it.  I thought it was completely unprofessional for the seller to defer to PSA for total respnsibility for determining that the card had been trimmed.

Fortunately for me, only four emails to the seller were required to get a refund.  Now I enlarge pictures on eBay and examine how cards fit in their plastic holders before I bid.  I’ve found several that I’ve decided may have been trimmed and declined to place bids. 

Clearly, this is LET THE COLLECTOR BEWARE when it comes to altered cards.  Kudos to the eBay environment for controlling buyer satisfaction and seller integrity.  I have bought on eBay one damaged card holder, a blue-tint card that was supposed to be green, had a card "lost in the mail," and a seller who must have discovered that his "buy it now" price was way too low and conveniently "misplaced" the card.  In every case, I got my money back--even though I would have rather had the cards. 

UPDATE (August 10,2010): After talking with several informed dealers, I've learned that it was possible with older PSA graded cards to pry open the old-style cases.  Possibly, the card I bought off eBay had been replaced for a legitimate 8.  In which case, eBay's grader may have not graded such an obviously trimmed card.  This possibility seems to be a likely one--we'll never know.

If you want details about how baseball cards are altered to appear better than they were, try:

http://www.alteredcards.com/