Nameko mushrooms are fantastic, but I would remind people that when you buy nameko mushrooms, do keep your common sense. So many people think that mushrooms look weird anyway, so they don't look at their mushrooms before they buy them.
When you buy nameko mushrooms, the first thing you need to look at is color. It they're kind of brown/gold, then you're good. If they're very dark or very light, then you might did better to find another source of mushrooms.
Also, although mushrooms are going to be a little slimy if they get wet, you shouldn't buy any nameko mushrooms that are overly slimy or mushy. This is usually a sign that they got wet, and will turn into mush when you cook them. Unfortunately, some produce sections still haven't caught on to the fact that you have to keep your mushrooms away from those little freshener sprayers.
Finally, I would urge you to buy organic nameko mushrooms, and of course as much organic produce as you can. It's not only better for the environment, but you don't have to worry about feeding yourself pesticides like you would with other foods. Just "food" for thought.