You should trust the color more than the fizzing.
from looking at the result charts, it seems that fizzing *with pure samples* tends to be a property of tertiary amines, such as yohimbine and (especially) BZP/TFMPP, and to a certain extent DXM.
however, smoking/fizzing is not necessarily a result of the drug itself. some fairly standard fillers (e.g. calcium carbonate, and possibly even lactose) will evolve a gas when reacted with sulfuric acid.
so smoking/fizzing may not be a result of the drug itself, but actually the fillers.. therefore smoking shouldn't be considered a characteristic property, except possibly for DXM.