goopy
Thick, sticky, and messy like too much glue or syrup.
Goopy describes something thick, sticky, and slightly messy in a way that's often unappealing. When you squeeze too much glue onto a project and it oozes everywhere, that's goopy. When someone leaves a jar of honey open and it gets thick and gloppy, it's gotten goopy.
The word captures that unpleasant texture of things that should be liquid but have become too thick, or things that stick to your fingers when you touch them. Goopy nail polish won't go on smoothly. Goopy oatmeal means someone added too little water. If your little brother gets syrup all over his hands and face at breakfast, he's goopy.
You might also hear people describe overly sentimental movies or songs as goopy, meaning they're so sweet and emotional they feel excessive, like pouring too much syrup on pancakes. In this sense, goopy suggests something has crossed the line from genuine feeling into sticky, uncomfortable mushiness.