The extremely high susceptibility of MCT to any external action is reviewed. The stability concept is analysed through two different approaches, at the microscopic and the macroscopic scales. The choice among numerous potential candidates to IR detection can be helped by some selection criteria; these include stability, which can be estimated through microhardness measurements, or ordering, which refers to the electronic properties. The II-VI mercury-based ternary alloys can be compared with other candidates such as pyroelectric detectors, silicon and low-dimensional solids, mainly III-V superlattices. Some futuristic materials or exotic structures are proposed through the application of band-gap engineering and structural engineering concepts.