Hi Stronghammer,
I agree with WillC; is it possible to post photos of each plant in it's entirety, showing the pot with soil? If we can see the entire plant and the manner in which it's potted, that will help in providing more accurate advice for correcting the issues.
I can't determine exact identify of the plants from close up leaf photos but the issue with leaves #1, #2 and #3 appear to be possibly a bacterial infection. Leaf photo #4 may be a fungal issue.
In photo #5, do the white things move/fly? If they move and fly, it's probably a white fly infestation. Mealybugs usually appear as small white cottony blobs.
I wonder if the plant you refer to as Dracaena elephantipes (Photo #5?) is actually
Spineless Yucca (Yucca gigantea) (synonym Yucca elephantipes).
Many people make their own mixture of insect soap for their houseplants by combining regular liquid dish soap, isopropyl alcohol (rubbing alcohol) and water. I did that years ago but as I've gotten older and lazier, I now just purchase Insecticidal Soap from Home Depot or Walmart garden center; it takes care of many different houseplant pests. Whatever method you decide to use, just be sure to completely saturate every leaf and crevice until dripping wet to be certain to get adult as well as any juveniles and eggs. You may have to spray once, wait a few days to a week and do it again to be sure to eradicate them all.