Zap a dap of Dew?

Ok I'll play dumb guy on this (easy for me). If its all that important for optics to adjust in temerature to the air then how can dew zappers not reek havoc with air currents and optics? Let me guess its still better that a 1/4" of dew?

I'm no expert, but I did read somewhere that gave the reason and it sounded good to me. I am paraphasing! it basiclly said that when objectives are cooled to the outside air temp they will often drop below that temp. so in order to really keep the temp stable you would have to apply heat. so you are really heating up to the outside temp, because the scope tube, correcter will not stay at the outside temp very long once it is cooled off.