Final answer:
The difficult smoke odor for technicians to overcome is the complex odor or psychological odor.
Step-by-step explanation:
The difficult smoke odor that technicians struggle to overcome is the complex odor or psychological odor. Complex odors, also known as mixture or composite odors, consist of multiple volatiles that interact with one another to create a unique smell. They can be challenging to analyze and remove because the perception of complex odors relies on the processing of various odorants in the olfactory system.