I don't have any luck finding reviews for miners, used or new, that have been made after some months or years of real world use experience.
Dozen's of 'unboxing' videos and similarly useless stuff is easy to find for many miners, but that's not what I'm after.
What's the best way to go about it?
This is a million-dollar question, if a miner is proven to be reliable it means it was out there for a long time and now it's probably not profitable to most people, so you either take the risk or wait until the gear is outdated, so that's generally speaking.
In some special cases, like the 17 series, reports were coming out about how terrible those gears were just a few weeks after the first batch, it was easier to avoid those models than say the S9k which took a while to prove how low-quality it was.
The second issue would be whatever reviews you find could be accurate "then" but not now, an example of that would be the Antminer S9, 2 years ago, those were still tanks, today, the failure rate on those S9s is pretty high, which suggests that the lifespan of those miners is coming to an end, and will require some series repair, I have said in this forum alone that S9s were tanks, based on my experience and many others that I know, when I said that back then, it was true, if you happen to read that review and not this one, then it's bad luck.
Most information you can gather regarding gear reliability would come from your own experience, and friends or people you do mining business with, hard to find such info publicly for free, if you want to ask about a specific gear or a comparison of 2 gears I would help to the best of my ability to answer based on what I know,