Saltpeter and sugar smells like,............well, burning sugar (caramel) when it burns.
Saltpeter is not the only oxidizer used in pyrotechnic mixtures. There are also the chlorates and perchlorates. Potassium perchlorate mixed with something that burns will pretty much go boom. We had a jar of sodium chlorate (weed killer) and mixed that stuff with some sugar and it kind of burned real fast leaving a huge cloud of caramel smelling smoke in the air.
I think they use ammonium perchlorate as the oxidizer in the space shuttle solid fuel boosters if I remember correctly.
Aspirin is acetylsalicylic acid, not ascorbic acid. Ascorbic acid is Vitamin C.