I'm not sure if you have spider mites or what, BUT if you force water rinse off your plants, then get a spray mister, fill the water mister up with water and add 2 TBLspoons of dishwashing liquid and spray the entire plant, under leafs especially.
The little tiny black things make me believe you have spidermites that thrive in dry places and suck the life out of the leafs. IF you tap on the upside of the leaves, place a paper under it and the spidermites will drop off onto the paper. The stickiness comes from their webbing when it's heavily infested especially at the tops of plants and the tops will start to furl/curl.
Mealybugs are small, whitish insects. They are about one-eighth to a quarter inch long and sometimes have a cottony appearance. Mealybugs can be removed by hand and then destroyed by wiping them with a cotton swab dampened with rubbing alcohol. A plant that is heavily infested should be destroyed.
You were correct in separating them from your houseplants
It certainly wouldn't hurt to use the water/soap solution to spray any plants that were close to the infected ones prior to taking outside. Be sure to get under all leafs.
Note of advice
: any time you purchase a plant or repot a plant it you should always make sure the new pot is clean and sterile
you never know what is still surviving in the older pots