In this puzzle, solvers often get stuck on the yellow group, which includes words like ASTERISK, CATCH, CONDITION, and STRINGS. The challenge arises because these words can seem related in various contexts, leading solvers to misinterpret their connections. For example, while all four can relate to legal or contractual language, the specific theme of 'fine print' may not be immediately apparent. Another common pitfall is the purple group featuring BRIDGE TROLL, MAD HATTER, RIDDLER, and SPHINX. Solvers might initially think of 'characters' or 'mystical beings' as a potential grouping, but the specific connection to 'famous riddle-givers' can be overlooked, especially since some characters are known for broader narratives rather than their riddles specifically.

To differentiate real groups from plausible decoys, solvers should focus on thematic consistency. For example, in the green group, the connection is clear as all characters are known for having green skin, which is a specific and unique trait. In contrast, the words in the yellow group, while they can be related to contracts, do not share a more straightforward, singular theme like the color or characteristic-based groups. Additionally, understanding the context of the words can be crucial; for instance, recognizing that 'pool' within the blue group refers to the Reflecting Pool rather than a swimming pool helps solidify that group’s connection to the National Mall.

A useful heuristic for future puzzles is to look for explicit thematic links rather than relying on broader or more abstract associations. When faced with a set of words, quickly jot down potential categories they might fit into and see if there's a common thread that binds them together. Another takeaway is to be cautious of words that can fit into multiple categories; identifying the most specific and narrow connection often leads to the correct grouping, as seen with the characters in the green and purple categories.