Just another example...
We bought a small teardrop camper last year (basically a king bed on wheels, with a small kitchenette on the rear under a clam shell). We used to car camp with a large tent - we got tired of sleeping on an inflatable mattress and wanted to do longer trips, so the teardrop made a lot of sense (we aren't ready to give up "camping" for "RVing", if that makes sense).
On day one, the solar controller (feeds power from panels to battery) was wired wrong. Fixed by dealer on the spot, but not a great start. Thankfully, this dealer has a solid post-sale/delivery-day walk through (not all do), so we picked up on the issue.
The wiring in the battery box is a bit of a rats nest. It's not wrong per se, but it's not as tidy as it should be, IMO. The battery lives in a storage box on the front of the trailer, alongside miscellaneous items (tools, bucket, hose, power cord, etc), so having the wiring untidy makes it more likely for connections to get broken.
The AC unit sits on a drain pan that's a bit too shallow for the job. If the trailer isn't nearly perfectly level, it will overflow into foot of the bed. Again, not wrong per se, but if you don't know in advance, you could be in for very wet bedding.
The brand is well-known and considered middle-of-the road. Not the cheapest, not the most expensive. We knew what we were getting into, and we're quite happy with the purchase, but if we hadn't done due diligence, we'd probably be a bit disappointed.