most tanks you see that empty their contents were not purchased brand new, but used.
so who knows what abuse they were subject to before the current owner had trouble.
in fact, I would argue that most tanks in the hobby these days are not purchased new. it seems like every new tank thread on here is from kijiji, craigslist etc.
Few people go to the LFS and buy new these days.
the risk of failure of used tanks is a lot higher than brand new tanks, although the risk is still there.
companies like Aqueon/Oceanic have lifetime warranties on their large tanks (over 65g), they are built to last.
the only catch is that most times you have to use their crappy ass stands to honour this warranty..but still, the fact that the warranty is there speaks volumes about their workmanship on their large tanks IMO.