Hiding something gives probable cause. In court it's used to show acknowledgment of guilt. Drugs are not the only thing they're looking for, and many "objects/items" have both good and bad uses. Consider the individual components in bombs such as: ball bearings, fertilizers, gun powder.. these are all legal things that may have been in the bag, but together or separately in large quantities may draw attention from authorities in a search and require seizure while under investigation.