Sorry if this is a n00b question, but after playing the core set at a friend's house I bought Gloom and three expansions, and I'm not seeing an obvious way on the cards to tell each expansion apart for storing later. Obviously, many of the cards are specific to the game play mechanics of the expansion, but some deaths and events are generic and after the game ends, is their a clear way to separate all the cards back to their original expansions?
You're correct in noticing that many of the Gloom expansion cards have unique markings that distinguish them from the cards in the base game. There are a number of Modifiers and Untimely Death cards that aren't marked, though, so my best suggestion is to check your decks against the Card Lists that can be found on each product page. You can find those lists by going to the main Gloom page on the Atlas website, then click on the specific expansion and look for the PDF in the yellow column on the right.