I think the issue is hit-or-miss. I have a 686+ from 2013 that's perfectly aligned.
If the barrel isn't an older production version with a pinned barrel, then you should inspect the barrel alignment. Pinned barrels are all perfectly aligned. The unpinned barrels can be canted.
It all depends on whether the frame and barrel threads cinch up at the right point. If the barrel can be twisted a little beyond dead center relative to the frame, and it's still within S&W's tolerances, it'll be sold that way.
I've seen people posting several recent (2017-2018) S&W revolver purchases on YouTube that have perfect alignment. Either the problem is no longer happening, or the canted ones were sent to another seller.
Best advice is to take time to personally inspect the exact gun you intend to purchase. Don't buy unless you're 100% happy with the barrel alignment.
Don't pick another brand it you want a 686. Inspect and enjoy.
