It stands to reason that the dried skin of an animal would naturally present some aroma. However, a rawhide chew really shouldn’t smell rotten or putrid; such an odor could indicate a high bacterial load. On the other hand, neither should a rawhide chew be completely odor-free! This would indicate that the product had been subject to extreme bleaching and chemical treatment.
The makers of good-quality rawhide chews say they use natural (and beneficial) collagen as a binder for these products. But since ingredients panels are not required for these products which, despite the fact that dogs ingest them, are not considered a food item by the Food & Drug Administration, there is no sure way to know what binding agent has been used as the product’s “glue.”