Note that my comments apply strictly to stuff I'm going to run, and also not from a major dealer where there's a warranty. I'm talking about stuff that's been around past any warranty, so it's basically "what you see is what you get".
I'm with Rocky Mountaineer on stuff like rolling stock, I don't mind buying that sealed, lots less to go wrong, not to mention a much smaller risk. I've personally experienced two issues with sealed boxes, one being the moisture issue and the other being a broken truck, obviously from handling. The moisture issue was not a storage issue, as it turns out, the Legacy T1 Duplex was one of the ones that suffered from incorrectly cured Styrofoam, and the release of moisture was from within. Obviously, probably everyone here probably knows about the Legacy turbine issues for the same reason.