Sophisticated improvised explosive devices (IEDs) challenge the capabilities of current sensors, particularly in areas away from static checkpoints. This security gap could be filled by standoff chemical sensors that detect IEDs based on external trace explosive residues. Unfortunately, previous efforts have not led to widely deployed capabilities. Crucially, the physical morphology of trace explosive residues and chemical “clutter” present unique challenges to the operational performance of standoff sensors. In this review, an overview of standoff trace explosive detection systems is provided in the context of these unique challenges. Tradespace analysis is performed for two popular standoff detection methods: longwave infrared hyperspectral imaging and deep-UV Raman spectroscopy. The tradespace analysis method described in this review incorporates realistic trace explosive residues and background clutter into the technology development process. The review predicts system performance and areas where additional research is needed for these two technologies to optimize performance.