To me, it seems variable...I've detected a sweet vanilla smell sometimes, and sometimes a rank offensive odor (on same plant) possibly depending on temperature and weather.

I've never had much scent from mine :(.

The leaves look like sweet autumn rather than the native C. virginian. Since SA is seed grown rather than a hybrid, there may be some variety in the scent. Is it possible that it was another plant in the garden, such as Nicotiana?

Thanks all for your answers.

Nhbabs the powerful scent was during daytime. And I could smell it upclose, when I took the picture.

Reminded me of a mixture of bitter / sweet almonds. I thought maybe it's flammula derived clematis....

I have a sweet autumn clematis that smells like jasmine and marzipan in cloudy weather, and like jasmine and cinnamon in sunny weather. It has no scent at all in the night. Would be nice to have vanilla scent, like the superb C. Montana at my moms house.
I went out and took a photo for you. Looks like the same plant as your neighbor's.

Pea

Pea thanks for the info. This one is definitely almond. I passed a 2nd time, and I could smell the almond 50 feet away, thank to the wind.