I've been having a hard time posting images.

[Bernardo de La Paz]

14. postimages is deceptive. It will seem to work, for the poster, but not others

The poster has the image in their browser cache so they always see it. If they clear their browser cache it will probably go away, unless maybe two things: the browser is at the same URL and postimages server remembers the URL. The latter is a big if and since I don't use postimages I'm not inclined to experiment.

I kinda sorta doubt postimages filters on political content, but again I haven't experimented so I can't say.

Premium (paid) postimage uses will always see all postimages.

The problem is that (I am almost completely certain) postimages throttles image traffic. So an image can posted and the first 100 (or some similar number) of people will see it just fine and it sits in their browser cache so even if the page changes on DU, they continue to see the image. But any more people looking at it get the blue square. The poster thinks "What's your problem, I checked and I see it just fine."

Don't use postimages: you will be fooled and most of your audience will not see it.