Thee's a reason they only put on average a 1 year warranty on them. 2 at most. And a 2 year warranty is no guarantee that it's built better. As far as the tires, frame and suspension goes. Look for bracing above the spring hangers. If you don't see any, run. If you can't pronounce the name of the tires, have them changed out to Goodyear Marathons, Maxxis, or Carlisle. As for the springs, look at the cargo carrying capacity. It should be as high as you can get. Stay away from trailers that have 900-1500lbs of CCC. By the time you load up with gear and maybe water you'll be pushing the limits.
For the most part everything out of Indiana is built the same way with a few variables that don't make one better, just different.
If you want something a little better then look at one of the smaller brands. Lance, Northwood, Outdoors RV, Airstream, Oliver or Bigfoot to name a few. All those have gone the extra mile to make something that will stand apart from the rest. Will they all have no problems? No, they all have problems. But having a solid foundation takes away one area that is susceptible to problems.
And you do get what you pay for.