I have a couple things to say, I'll try and split up my posts as they are kind of mutually exclusive.
First and foremost:
It is my personal opinion that trying to have these kinds of feedback threads DO NOT AND WILL NOT EVER WORK.
I find that in a lot of ways, it's kind of like /r/gonewild except for that there are no females and none of the guys are gay. Everyone wants to post their massive dick pic, but none of those people posting them want to look at other pictures of dicks. Maybe if they're like 17 inches long or some crazy shit but even then they just don't care.
A better way to go about having producers give/get feedback is in a live context, much like the one we used to have over at plug.dj and now currently have at sharcu.be.
The idea is that everyone gets in line to play one song. When it's your turn, you play your song, everyone listens to it at the same time and can comment, and then when your one song is done, you go to the end of the line.
This way, you get real-time feedback, you can interact with the people giving you feedback, and there is an incredibly minimal amount of bullshit feedback.
Now, with that said, this doesn't really help our dilemma on this website, so I want to try and weigh in with my 2 cents about how we can try and improve it as a relatively small, tight-knit community of producers.
I believe the best way to get people to post feedback is to not allow someone to start a new thread in the feedback section unless they have posted a minimum of three comments in the feedback section. Shouldn't be terribly mind-boggling to code, and in order to fight shitty feedback (which is pretty much always going to be a thing), you require those comments to contain at least fifteen words.
Obviously this wouldn't completely remove spam (people could always just copy/paste a word ten times), but if it was compounded with a system where users could flag comments as spam, you could really keep spam at a minimum since it's very obvious when someone is insincere with ten words. To further streamline the process for mods, you could say that if 5 different people flag it as spam then it is automatically removed. I don't think 5 is too low of a number because really what motivation is there for someone to want to remove someone's comments?