Mildew or Mealy bugs in my house plants?

Hi there, I have two plants, one is a china doll and the ivy. I noticed a little while ago that my china doll was experiencing some drop leaf and I thought I may be over watering it. I ceased watering it as much and it seemed to be getting a little better however today I noticed tiny bundles of white fluff all over the china doll as well as a few little bundles on the ivy (not in the soil). Then I umed it was mealy bugs so I sprayed it with an alcohol/water/soap solution. My question concerns the fact that there is a white powdery substance on the terra cotta pots that both of my plants are in and I've never heard of mealy bugs leaving white fluffy stuff on a pot before, just on the plant. That coupled with the fact that I cannot actually see any insects brings me back to thinking it's mildew. I don't want to get it wrong because if i continue to spray the water solution I'm afraid mildew will get worse. Help?!