The reason why this would most likely be difficult is this: Almost all items in the scene can be classified as physical evidence.
Why the task would be difficult
In addition to the fact that many items could qualify as physical evidence, there is also a tendency for physical evidence to be easily contaminated by people who are not wearing gloves or booties, or by touching objects with bare hands. This can make it difficult to determine the origin of the evidence and to link it to the crime.
Also, some types of physical evidence, such as fingerprints are very fragile and can be easily destroyed if they are not handled properly.