Most Topps packs compounded the "sticking" problem with wax-sealed paper, which often stained the card surface, so rubbing residue off with a sock is one of the earliest things I learned about their "maintenance." (Just in case, here are some more ways to remove wax stains.)
There's no gum or wax on Mr. Combs, partly because commercial chewing gum didn't get married to cards until the 1940s. Instead, Boston-based United States Caramel Company packaged these high-contrast players with slabs of caramel, each package containing one card and one piece of candy. (They must've used a buffer between the two, since Earle--not "Earl"--came out clean.)
US Caramel produced this scarce set of 32 sportsmen (included 27 baseball players) and offered a baseball or glove in exchange for complete sets. Like other promotions, the "catch"--no pun intended--was #16 Charles Lindstrom, who they severely short-printed. Less than a handful of his cards survive today, a white whale for what's already an expensive hunt.
#28 card front
US Caramel cards prove so rare that I've been unable to find a #5; the first two scans come from a (super expensive) eBay listing. This #28 Ed Brant--actually "Brandt," another misspelling--does come from my collection and cost much less. If you've got a Combs to trade, let me know!
#28 card back (number torn off)
Value: Low-grade cards run at least $30 and will vary considerably, given their short supply. Superstars like Ruth and Gehrig go off the charts, well into the thousands.
Fakes / reprints: Unfortunately, plenty of fakes exist for Ruth and probably most of the others. Be very careful when purchasing Caramel cards; expert forums like Net54Baseball.com are one place to seek guidance in rare card shopping.