Depends.
Contrails either come from the engines or (for example) the wing tips.
"Chemtrails" come from wherever the CT's (Conspiracy Theorists) pull them from.
Seems an appropriate place to put a quote I just wrote down:
The general policy of the press had been stated by a famous editor five years ago. "There are no objective facts," he had said. "Every report on facts is only somebody's opinion. It is, therefore, useless to write about facts."
--...
Floppy disk?
That was punch-card tech.
The story goes that on an early NASA mission, the engineer in charge
of the weight control demanded to know the weight of the software.
He would not take for an answer that it had no weight and demanded
to see it. Finally he was shown a deck of punched...
Obviously, you don't remember the Tylenol poisoning cases, and the subsequent focus on tampering.
What's the point of a secret evil plot, when it's detected immediately?
Always better to do your secret evil plots in a novel manner. Gotsta have style!