I was waiting for a strong response I don't find that they smell much unless the male is in flower or you start busting out branches. The smell reminds me of some of the eucalyptus species. The tree in the photo above is on an island off the coast of Rhode Island. Ailanthus has naturalized there and is actually quite nice looking in the setting and the trees are very healthy. It doesn't seem to propagate in the expected invasive manner, the ocean weather and native shrubs and trees keep it in its place. In the city the health and structure is usually pretty bad from growing up in alleyways and between sidewalk cracks etc.

Here's my hulking neighborhood ailanthus (on the left) which throws down a big branch once in awhile, this one during high winds:

-moss