It's spider poop and because it's partly protein based, it dries solidly.

They won't just wipe off. Try leaving the cleaner soaking on the spots for a while, then use a scrubbing sponge gently.

I'll give it go -- thanks.

Trying wetting with liquid cleaning solution (Fantastic,windex,etc) , then use an old expired credit card as a scraper.

I tried different things on my spider poop. Endust worked the best, and tomorrow I'll give Armor All a try. Edit: Don't use Armor All, it contains silicone.

Denatured alcohol was good, but it left a white haze on my vinyl siding. Low emission paint thinner was poor. First try out everything in an out of site area, looking for damage and changes to whatever you are cleaning.

Details: I have a pale to medium green vinyl siding. It is under a portico or porch roof so I have the tiny black dots and larger smudges on the walls. I sprayed on some Endust, and scrubbed with kitchen pad with plastic scratcher on one side. Some dots and smudges came right off, but most took 10 to 20 scrubs, some even more. One or two did not come off yet. Letting the Endust soak for a while seems to help.

Important: The Endust spreads some of this black goop around, so wipe it off with a clean cloth.

It leaves an oily film, like Armor All does, so any edge between cleaned and not cleaned shows. I do not know for how long this oily film is visible. It looks good, like Armor All does for a few weeks. Endust seems a lot like Armor All, And Armor All works OK, so tomorrow I will try it some more. It has to be cheaper.

I used Endust on a strip of Acrylic Latex white paint. The spots were way more difficult to remove from the paint. Some stain still remained, and the paint is all shiny from the oily Endust.

Edit: The next day the areas with AA and Endust were both covered with tiny bugs that got stuck on the oily films. The bugs came off easily with a broom, but now do I need to do this often? I Googled AA and found that it contains silicone (like Pledge) and so it creates a major problem if paint is applied over it.

Edit: Endust contains oils, so I would expect problems if painted over with latex paint. Oil based paint may also be a problem, but I don't know.