Once upon a time, when D&D was still new, just about everyone at GDW made a photocopy of the basic D&D books because they were not yet available in enough volume for everyone to have their own copy.
Once the sets became available, we all went out and bought them and discarded the photocopies... which were just inferior.
If someone makes a photocopy for his or her own use, that is called fair use, as long as it's not the whole product, and as long as its not for resale. That includes copying someone else's copy of the product.
That is especially true if the product itself is not currently available (ie CT or MT, probably not for T4).
When someone starts photocopying multiple copies for others, then it gets to be infringement.
Personally, if you want a specific work which isn't in print and you can get a photocopy, I think that's OK.
With thanks to David J. Golden.