Operational deception is a problem for MI analysts and commanders, not for recce folks in the field. They report what they have.

Large-scale deception works rarely, and almost never without the assistance of the fooled ones. The German army had almost no air reconnaissance on the Eastern Front after summer of 1944 and never got seriously surprised again.
Large operations require large preparations.

I'm sure it was possible to learn about Tet in advance as well, but sometimes MI and commanders provoke being fooled by being too fixed in their beliefs.

Nevertheless, recce can yield the opposing commander's intent.

Again - judgment of recce reports is not the problem of recce folks in the field.
Everything can be misunderstood - even orders (charge of the light brigade...).