Sometimes I'm buying things that look like leather but you can't easily tell. I sometimes use the sniff test. Is there any other test for determining if an unlabeled item is leather or not?
Besides reading the labeling and testing the smell, there are some things you can look for:
Looking very closely, does it have pores (real) or only a pressed texture (fake)?
The hair follicles provide the grain pattern that is so much a feature of the value of the leather... In most animals the grain pattern is uniform, in terms of both regularity and distribution over the pelt.
Covington, Anthony D. Tanning Chemistry: The Science of Leather. Cambridge: The Royal Society of Chemistry, 2009. Page 36. Print.
Are the cut edges rough or very smooth (some fake leather will have very smooth cut edges)?