I would say that the conclusions are not necessarily the problem, rather the delivery. You don't have to spell some things out so matter of factly, you can infer them through conversation. Also, you should be more specific with your delivery, rather than being vague. For an example consider the first part of what you've written:
John sighed, and thought for a moment, but the conclusions were fairly
obvious. "You're an occultist, and a remarkably mature one for your
age. You've progressed from tacky trappings to real artifacts, that I
imagine are greatly desired in your circles. I'd guess that you've had
a mentor of some esteem.
First off, why mention "the conclusions were fairly obvious"? This should come out from the way the character talks and behaves. Unnecessary.
I get the impression you want to show that he finds this "explaining" to be tedious, because he considers things to be obvious. So why don't you show it? He's a man of intellect, and when people like that think things are obvious, then they can be condescending. If he finds it obvious, he probably assumes other people do, too, so why should he bother telling them what they should already know?
Also, the things he reveals are not that earth shattering, and are rather vague. What makes this person he's talking to mature? What real artefacts? Why would he "guess", when he clearly knows?
Consider this dialogue instead (okay, it's definitely not perfect, but I needed something to illustrate the point).
"I'm curious if you know why you're here?"
"I don't play games, Miss Pollock."
"And then what? Shall I juggle? Roll over? Fetch?"
"Come now, Mr. Peel. I'm just interested in what you think."
"Judging by that volume of Reading the Mind - which, if I'm not
mistaken, is only given to members of the Red Sash - you should be
fully capable of knowing what I think."
She tilted her head in acknowledgement. "I consider that to be bad
form. And bad for business. Unless requested."
"Young, gifted, and mature. A rare combination, no doubt thanks to
your rather wealthy benefactor."
"Good guess. You know, you could get yourself a crystal ball and set up at a flea market,
you'd make a killing."
"I never guess, Miss Pollock. I observe, and what I can see is that he
has infinitely better taste than you in artwork." He pointed at the
oil painting hanging off the wall, the black and white crow seemingly
trapped within the canvas. "I'm not sure I would hang a Raphael next
to your cheap Dali fakes."
See the difference? You're demonstrating his in-depth knowledge, his intellect, his disdain i.e. his character. Also importantly, you're helping introduce conflict, and you're creating a specific scene rather than just referring to vague things like "shelves", "objects", "tacky trappings", "real artefacts" etc.
The logical conclusions reached are based on his intellect and his character, so you should show us that character so we know how and why he reached those conclusions.