The hardness of rubber in slippers does not necessarily indicate the quality of the product. Hard rubber can make the slippers more durable and long-lasting, but it can also make them less comfortable to wear, particularly for long periods of time.

The quality of a rubber slipper depends on various factors like the materials used, the construction, the design, the brand reputation, and the price. A slipper made of natural rubber, good stitching and construction, comfortable, eco-friendly and with a good brand reputation at an affordable price is considered a good quality slipper.

It’s important to look for a balance between durability and comfort when choosing rubber slippers. It might be a good idea to try on different styles and see which one feels the most comfortable to you. And also, make sure to check for certifications and warranty before purchasing the slippers.