I have an Ender 3 clone, a Voxelab Aquila, that I got as an open box. I think its bed is a little warped, or it's possible there were some parts that were not perfectly square that I still left alone when I finished putting it together. I don't have auto-bed leveling or anything.

I will not say it's trouble free, but it's no nightmare. I have to tram every 5-10 prints assuming I don't try to get the print off the glass plate without gently removing it from the bed first. I also wipe with a little alcohol before every print, and occasionally use a little gluestick if it's being a butt, but overall it's all very livable. Tramming can be tedious as it's never quite perfect, but I generally get good first-layer adhesion (especially if I use a brim), with a touch of elephant foot. For a hundred twenty bucks two years ago, it's been a good purchase, though these days I think you do better even without hunting for a MicroCenter Ender.