Dirtpig ( what a name
)
It would be so easy without bugs and similar pests!!
Before I moved my plants inside, a week or so before I sprayed them all with Bayer Advanced Rose and Flower Care. (at 2 ounces /Gallon) It contains pesticide, fungicide and fertilizer. The pesticide is Imidacloprid which does an excellent job on Mealies, Scale and more. Since it is a systemic, it will keep the plants clean of bugs for some time. During the Winter I simply keep an eye out for bugs and clean them up immediately before they become real trouble. Sometimes just washing them off, or using Safer's soap, or similar keeps things in check. If not, I also use sometimes Orthene.
In Spring all my plants go outside, get checked for Bugs and if necessary get the Bayer treatment. This Spring I had to make a bucket with the diluted stuff and I actually soaked a couple smaller Orchids which had Scale. It worked. ( I wear gloves)
I would think vigilance is definitely the first step in keeping plants clean.
Btw Hoyas respond very well to the Imidacloprid treatment. In my hands it is the only way to grow Asclepiads.