I ask myself this question everytime i come across a collection. Many times a collector or collector(s) opened up a pack of cards many decades ago and immediately put the card in a baseball card sleeve or other protective case. This card was only been to be retrieved decades later when the owner wants to sell the card. Any prospective buyer would have to examine the card very thouroughly before making an offer. Therefore, the card must be taken out of the sleeve or case to inspect for creases, centering, trimming, etc. Many times the owner does not want the card to be removed, for obvious reasons. However, the seller needs to think of himself as the buyer. How would you like to be shown an item, and then be told you can not inspect it. You would laugh and walk away from the deal.
One thing that was quite common some time ago, and still is today, is trimming of cards. Basebal cards are trimmed to shave down the rough corners. The card will then look like it has four sharp corners. Trimming is sometimes tough to decipher to the naked eye, but a careful measure will determine if the card has been trimmed. I got a call from a guy on the east coast with a great baseball card collection a few months ago. When i told him i wanted to take each card out of the sleeve, he thought i was nuts. He told me the history of how the cards were obtained. He couldn’t understand why i wanted to measure the cards. If i am going to spend thousands of dollars, i must be satisfied with the cards. Needless to say, I walked away from the deal.
As a private colllector, I am always top dollar for baseball cards, but I have to be able to measure them and inspect for creases with a magnifying glass.