I too generally clean a new to me gun before shooting it for the first time.At range this summer, dude took table next to mine and pulled new AR-15 out of the box and proceeded to load magazines.
I asked him if it was a new rifle, he said Yep, just left the gun store.
Then I asked him if he cleaned it yet.
He said no. I asked him to move a few tables away from me.
He got puzzled, almost insulted look on his face and asked why.
Told him if there's any factory dirt/grease/metal particles in that barrel,
it's going to blow up on first shot.
Didn't believe me that a new gun could be dirty, so I ran a freshly cleaned bore snake through his rifle and he couldn't believe how much gunk stuck to it.
He went home and cleaned the rifle, came back next day.
I say generally, because I always carefully inspect a new to me gun before taking it to the range. Sometimes they are pretty clean and just get a quick run of oil on a rag through the barrel.
But I have bought "new, unissued" antique military rifles that had so much cosmoline in the barrel and elsewhere that they took hours to clean.
Always check a new to you gun for cleanliness, and especially barrel obstructions. May save your life. Many shooters don't seem to know that.