Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Worst stamp pad ever

I'm not sure why I got suckered into buying another Melissa and Doug art product since the children's watercolors were such garbage, but I guess I thought it would be hard to screw up a stamp pad. I was wrong. The colors are incredibly weak (which incidentally is the same problem I had with their watercolors) and don't show up when stamped. If the kids (aged 8, 6, and 4) pushed HARD they would show up faintly, but otherwise we might as well have been using invisible ink! I love the wooden toys by this same brand but I will never buy more art products from them. We are all very disappointed with this product.