Experiences with spot touch-up of wall paint?

Phew, ok. I actually misunderstood that. Ok, the eraser sponge is good, but not for everything. We have problems with the colored walls, either the "repair" is too dark or too light. White also changes its color due to the climate. If you are comfortable with the "dry smudging," then just do it that way. I would probably also use a round blunt brush and dab with the front bristles.

Ok thanks to you. Maybe what I'm making isn't so bad after all. Live I see it immediately, but almost not at all in photos. Only in 1 out of 4 pictures can you see it:



But don't get me wrong, the dark edge on the left is due to the poor lighting, the paint color is already a nice white everywhere. But where the arrows are, there are slightly lighter spots from the new paint. In the picture, I painted about 1/3 of the surface in the middle anew, and you can see it at the transition.

By the way, this is the basement where I did my first trials before tackling the other floors. ;)