When evaluating Mini Spray Fans, prioritize battery capacity (mAh), typically ranging from 1200mAh to 2500mAh, to ensure a continuous runtime of 3-8 hours. The atomization technology is crucial; look for ultrasonic high-frequency oscillation which produces a finer mist (micron-level) that evaporates quickly without wetting clothes. Additionally, check the motor type, where brushless DC motors are preferred for their lower noise levels (<30dB) and longer service life compared to brushed alternatives.