Fragranced Soaps, Shampoos
... and other fragranced shower products.
Consider that wet activates fragrance, so if you use fragranced products at other times, showering is likely to agrivate it
Far better to refrain from fragranced hair care altogether if possible. Also, make sure you have time after showering to allow hair to *fully* dry!
If you are unsure of your products, try a productless shower on meeting day or the day before and rinse, rinse, rinse.
The current trend in fragrance formulation is toward using powerful long lasting synthetics at higher levels. 
3. Perfumery: Practice and Principles; Calkin RJ, Jellinek JS; pg 139; John Wiley & Sons, Inc, 1994