Clingty
The product that you cannot get to at the end of a bottle / tube.
For example:
When you get to the end of a toothpaste tube, and know that there’s at least two more ‘squirts’ there, but there’s no way to access them.
Another example is ketchup. In many ways this is worse, because you can see the ketchup in the bottle. It’s lurking in the corners, but you’ve no way to get to it.
The person who overcomes the ‘clingty’ problem will certainly win a Nobel Prize. Many have tried, ALL have failed.