I do check that it fits and that he's delivering what I've asked him to deliver. And if I don't know what a good custom suit should be, then I should not buy one, or I should seek assistance in its purchase.
I don't own a custom suit but I assume I'd be in the room when they were taking my measurements and I my eyes would be open, so I could see the tape. And then I'd try it own before agreeing to taking it home. I'm not sure which side of the argument your analogy is on.
I do a lot of back and forth with our lawyers on terms. I read all of it and give feedback.