Me: “The lights are too bright, right?” (Hardware product)
User: “No they are fine but I wish the display was larger.”
I think questioning like this makes user comfortable criticising you.
The next step is to just differentiate between actual feedback and opinions that are intertwined in so much of the information the user could pass to you haha.
I've found by starting with my own insult/complaint, people feel more comfortable to open up a bit.
Not just specific to products, btw, but anything you want an honest opinion on.
Unfortunately it also means I can seldom enjoy anything and other people find me annoying. :/