That water has all the impurities that went through the air filter and "stuck" to the evaporator coil.
I used to work in the HVAC/R field, and cleaning evaps of heavy smokers was NOT a fun job!!
Also, any environment, such as body shops, photo/ printing shops, or beauty shops which have a lot of chemicals in the air are VERY hard on heating and cooling heat exchangers. The chemicals literally corrode the equipment to death.