That doesn't help me -- essentially, you just replaced the word "conscious" with the word "suffering" and that does not clarify much.
Let's try it this way. Here is a black box with something inside it. It does not communicate in any way that's meaningful to you. How can you decide whether it's conscious or capable of suffering? What would you need to measure or observe? What are your criteria?
Tabooing doesn't work here, you can only taboo your terms so far before you've completely severed yourself from the semantics of your language. If you don't understand what suffering is at a visceral level then no experimental contrivance will clarify the notion for you.
This seems significant:
http://www.theguardian.com/science/2015/aug/18/first-almost-fully-formed-human-brain-grown-in-lab-researchers-claim