Spongy describes something soft and full of little holes that hold air or liquid, so that it squashes down when you press it and then comes back up. It is a word about touch. Fresh cake is spongy. So is wet moss, so is ground after heavy rain, so is a cheap mattress, so is the inside of a bone if you cut one open. The bounce matters. Something can be soft without being spongy — mud is soft, but it stays where you push it, so we say soft or sticky instead. Spongy means the air inside pushes back. Whether it is praise or complaint depends on the thing. In the kitchen it is good: a light, spongy cake is what the baker was aiming for, and British people even call a plain cake a sponge. Everywhere else it usually worries people. Spongy floorboards mean water damage. A spongy brake pedal means air in the brake line and is genuinely dangerous. Spongy gums send you to the dentist. So read the noun after it before you decide whether the speaker is pleased.