Possible Clues:

• Sticky wet material or sickly sentiment
• Endless supply of wholesome syrup
• Hair gel, for example
• Excess epoxy
• Virtuous, refusing daughter's sentimental language
• Melted ice cream, for instance
• Sticky stuff fool fathoms out
• The sticky stuff that could, oddly, grow on ...
• Sticky gunge
• Sentimentality is not entirely desirable