It always annoys me when I download another Android app that actually works and would be very useful to have on my ereader but the UI looks plain ugly. The ugliness per se is not a problem, but try to read pastel text on white background or a very fashionable these days grey text on grey background and soon you will be heading for the delete button.
However, if you are willing to put some effort into it, there appears to be a way for making design corrections.
Here is an example. A popular off-line dictionary app
ColorDict looks like this straight from Play store:
You can't see what you type, you can't see the history, the icons are too pale, and you can't see what dictionaries you have and enable/disable them. Well you can try blindly but it's not very nice. With a bit of tweaking though:
I will soon be writing a little tutorial how to go about making such corrections (if there is interest). Meanwhile, do you know any ugly ducklings that you would want to use but the UI stops you from putting them on your ereader?