Safe, easily detectable gas or aerosol for testing fume hoods
Smoke generation is preferred over smell, as the visual test is a bit more objective. See this reference for more info, although $\ce{TiCl4}$is not available for home use. There are hobbyist alternatives such as smoke matches which will help you test the fume hood performance. (The above link is just an example, I did see better prices at less-known websites.)  An anemometer might be of help as well.