No, properly is not subjective. It means to build a wheel so that it won't loose tension and it stays true. Wheels that need to be glued or re-trued after 100 miles for break in were not properly built.
If your wheels come out of true because you hit curbs, bunny hop, etc. that is because you are not using a strong enough rim for your riding conditions and have bent the rim or because the wheel was not properly built. Not because the spokes have lost tension in a well built wheel.
Well, not everyone I have built wheels for has given me a log of their miles, riding conditions, etc. But I do know that the wheels that I have built for people I see regularly and myself have never needed to be re-trued and I do hit a lot of pot holes. I travel through a city that has some of the worse roads I have ever seen.
My only guess why your wheels with glue are better than the ones without the glue is because you are not building them properly and need the glue to keep the spokes from losing tension. Which sounds like the case since your spokes fatigued after only 50,000 miles. Spokes should last through many rims before they fatigue.