We have sold many "Brand New" regs w/ full warranty here on Hot Deals!
We have also sold many more " Used" regs, B.C.'s & computers here on SB. These used regs did not have the warranty from the manufacture.
As far as needing service, it depends on the condition of the gear.
But I think the OPs post was directed towards used gear, not the shops selling new gear with warranty. I'm a huge fan of hot deals, and appreciate the savings!
And if we're back to the comparison, used gear from a shop I normally put in the category of "certified pre-owned"
I'll shut up now, I don't want to get into a urination contest with anyone over this...