The novel is Crompton Divided (aka The Alchemical Marriage of Alistair Crompton) by Robert Sheckley; maybe you will recognize one of these covers. It grew out of Sheckley's novella "Join Now" (aka "The Humours"), published as by "Finn O'Donnevan" in Galaxy Magazine, December 1958, which you can read at the Internet Archive. The novella does not match anything in your description except the part about the protagonist going to another planet. The quotations below are from the novel.
The protagonist, Alistair Crompton, is a perfumer in the employ of Psychosmell:
Shrewd businessmen organized the Extraterrestrial Fragrances Guild, and kept it a close monopoly. The moderately well-off could buy any one of a dozen commercial scents, all with memory-releasing powers. The wealthy could go to a firm like Psychosmell, and, for a price, have an expert like Crompton mix an individualized fragrance for them, tuned to the configuration of the yellowish-brown fibers deriving from the ganglionic cells in their olfactory bulb outcrop. A man like Crompton was capable of pinpointing specific olfactory-memory hookups and their stimulators, and was thus able to produce memories on demand.
But Crompton's finest work, his greatest challenge, and the ultimate testing of his skill, came once every five years when the Board of Directors of Psychosmell assembled from various worlds and met at the mother company in New Jersey. For that occasion, it was customary for the Chief Tester to concoct a specific substance for the world's greatest gourmet of smell—the legendary John Blount.
Crompton had full data on Blount's olfactory responses. Working with infrared photographs of olfactory cell output, with catalytic balance levels, with chemical analyses of the aqueous mucus covering Blount's ganglionic cell fibers, Crompton prepared his masterpiece.
Crompton goes into space in search of his missing personality components:
His mind was made up. But there was a practical difficulty. To Reintegrate, he would have to travel to Aaia, and then to Ygga. Interstellar travel was expensive; and Aaia and Ygga were situated half a galaxy apart.
There was simply no way he could get together the considerable fortune he would need for his fares to these distant worlds and his expenses once he reached them.
No legal way existed, to be precise about it.
Crompton's seatmate on the flight to Aaia is an Aaian telepath:
"So you can read my mind," Crompton said, and looked at the person with attention. He saw a fresh-faced young man with a crew cut, wearing a gray sweater and white buckskin shoes.
"Yes, I can, when I put my mind to it."
"That is an invasion of my privacy," Crompton declared.
"What makes you think so? When you broadcast words, you expect anyone around to hear. Why not when you broadcast thoughts?"
"I want to select the thoughts I broadcast," Crompton said.
"Do you? What a curious attitude. One thought is very much like another, you know. They're just a sort of vibration and there's nothing personal about them. Creatures have been broadcasting words and thoughts at each other for a long time now, and no one is much better or worse for it."
"Aren't you sort of young to be spouting all of this deep stuff?" Crompton asked.
"I am not quite a million years old," the person replied. "On a galactic scale, that's pretty young. Still, I've seen a thing or two in my time."
"I don't find that a very amusing joke," Crompton said.
"I am an Aaian," the young man said. "I always tell the truth, even when I lie. And all Aaian jokes are in bad taste because we're too old to bother being subtle. I see that some proof is called for."
"I should think so," Crompton said.
"Then dig this." The fresh-faced young man reached up and touched his nose. Immediately his face changed to the deeply furrowed mask of an old man. His clothing changed to a tattered gray bathrobe, and his voice rose to a squeaky soprano as he said, "One good metamorphosis is worth a million words."