A.M.
I never had any luck with cool mist humidifiers. Plus I felt that they made the room slightly colder than I wanted. However, warm mist humidifiers do work better. It is true that they build up bacteria and such, but it is direly important to remember to clean them out everyday as we do. We have not had any problems with our warm mist humidifier and we have had it for over a year without any bacteria build-up.
Pregnant first time mom and pediatric nurse practitioner