Hmmm, thats a good question. I've never quite been able to put my finger on exactly what it is that it's supposed to smell like. Whatever it is, it smells nice!
I can't think of anything that it smells like, besides just being the essence of crisp clean.
The only thing that truly smells like <span style="text-decoration: underline;">Gain</span> would be the powder Original. To me the liquid smells completely different, and the Mr. Clean liquid and other various products with the "Gain" scent just don't smell quite like the original powder.