On any windy day, you can watch large flakes of limestone blow off the walls of the Sphinx quarry.
This is typical of Haloclasty.
Arguments against this usually include that other monuments don't exhibit the degree of weathering we see at the sphinx. They usually state these monuments were created from stone "quarried from the same limestone beds" as the Sphinx.
This is not true, however.
The sphinx is composed of three overall layers of bedrock that vary greatly in hardness and durability. They are referred to as Member 1 (the base, reasonably durable, and used for construction), Member 2 (majority of the body and crumbly, not at all suitable for construction or monumental artwork) and Member 3 (the head, the most durable layer, also used for construction.)
The head of the sphinx, and several other layers, is harder that the rest. The majority of the limestone the sphinx was carved from lies in a bed that was not used by the AE's for construction or monuments because it is a very poor choice for such usages, being too soft. The parts of the sphinx that show very little erosion (like the head and the base) come from the limestone layers that were used for construction.