Wall-climbing quadrotors represent a promising class of hybrid aerial-terrestrial robots capable of operating on vertical surfaces, confined spaces, and hard-to-reach environments. Recent prototypes such as PerchMobi3, Bogiecopter, and Duawlfin have introduced novel mechanisms including negative-pressure adhesion, unified actuation, and power-reuse strategies, enabling seamless transitions between flying, ground locomotion, and wall climbing. These designs address critical application areas such as infrastructure inspection, industrial maintenance, and disaster response, while also demonstrating improved energy efficiency and adaptability. Despite these advancements, challenges persist in terms of operational safety, energy consumption, adhesion reliability, and mechanical complexity. Current research is increasingly directed toward enhancing autonomy, developing lightweight structures, and exploring alternative adhesion techniques such as electrostatic and passive adhesives. This review synthesizes recent developments, identifies persisting limitations, and highlights future directions that can expand the adoption of wall-climbing quadrotors in real-world industrial and emergency scenarios.