A noun for “phony” or an alternative to "phoniness"
Solution 1:
I would feel betrayed by the deception.
Solution 2:
Fraud sounds like a good fit for your example of the fake trees. It matches one of the definitions from Merriam-Webster very well:
a copy of something that is meant to look like the real thing in order to trick people
Solution 3:
artificiality, artificialness, fakeness, imitation, bogusness, bogosity, falseness, ersatzness, dumminess,...
Look up synonyms for bogus, and then adapt to get nouns...