The great thing about Costco is that everything they sell is reliably fine. Is it the best in the world? Probably not. But it's usually good. At worst it's average.

When I find myself reading Consumer Reports or The Wirecutter looking for "what is the best toothbrush" it's not that I actually need the best toothbrush. I'd be perfectly happy with a good toothbrush. What I'm trying to do is avoid spending a bunch of money on something that looked like a good option and turns out to be ineffective, unreliable, short-lived, or otherwise terrible. Most retailers are absolutely overrun with trash now.

Generally at Costco it's not a worry, if it's a crappy product they're not selling it.