Its a good question. Reminds me that we used to have a long thread for happy FR owners that was fun to read.
To answer the question, my current trailer was the only new one we've owned. Had several used ones prior to this. We've had few problems (ripped seam in the dinette cushion, wonky radio, and an LCI jack that failed). Nothing big. I think the small items are to be expected. The question might be "how many have bought a new trailer without major issues?" I'd be in that category.
DW, 3 Kids and our Goldens
2012 Shamrock 233S
2008 Toyota Sequoia 5.7L 4WD