SpMp is one of the prettiest open source android app I've seen. It's a complete free youtube music client

I disagree. "It's ugly" is valid criticism. It has the same value as "needs better/more appealing graphics". You're just annoyed it wasn't sugar coded. In fact I'd argue the former is more valuable than the latter because it doesn't beat around the bush and more importantly it points to a problem rather than the solution.

As a designer I find that most often customers don't hit the mark by trying to design the thing themselves, telling me exactly what they want, essentially trying to do my job for me. Hearing the customer's problems with it to figure out a solution on my own as a designer is better a vast majority of the time.

"I don't like it" is bad. "I think it looks awful" is better. "I hate the colors" is best. I don't really care about wording, I care about the information I get.