Posted By:
PaulA trimmed card is one that has had one or more of its edges (borders) cut off partially or completely. Sometimes, this was done by collectors many years ago to fit the card into a smaller frame or for reasons that you can only imagine. Sometimes, modern unscrupulous collectors and dealers will trim a very small amount off of one edge in an effort to make the corners appear sharper, passing off a lower condition card as a higher one. Trimmed cards are worth significantly less than untrimmed cards.
Never heard of skimmed, but a skinned card is one that has had its back removed. This most commonly occurs with the Old Judge cards from the 1880s. Skinned cards are also worth significantly less than complete cards, though I suspect that a skinned Old Judge probably retains more of its value than a skinned Topps card.