Yes, there are those horror stories. But you’ll also find the opposite. Beautiful machines (many of them easily outperform all factory built) from very capable craftsmen, assembled in thousands of hours to their own highest standards with care taken for every little detail, perfection in mind.
Btw: My plane is somewhere in between 
You just have to search for a homebuilt from someone, who loves the building at least as much as his wife 
I have never heard any of those horror stories, but I have seen one or two on the internet from the USA. The usual thing is people do stupid mistakes especially when just starting up. Then they either give up, or start over again. I have built two horizontal tails for my RV-4 myself Similar things are much more usual than what non-builders thinks, but they are not horror stories, just part of the process. When you are finished and have enough scrap metal left to build another plane, then you have done a good job It’s easy to do a mistake. Usually it can be fixed, but not always without some patchy looking result. Structurally it is OK, no problems at all, but it’s irritating. With modern kits with matched holes and not to speak of these “factory homebuilts” things are much easier and mistakes are fewer.
Today I only look at the engineering aspects. I am not good enough to build home-made first class furniture like some very few people are, and I never will be. I only look at things like the rivets are set properly, the edge distance is OK, things are straight within tolerances, no crack inducing corners or edges and so on. An extra hole here, a protruding head rivet there because I found no easy way to dimple in the confined space, or a few patches here and there, I really don’t care. As long as it’s nothing wrong technically, I’m fine.
I also think that with wood or composite, things are much easier to hide. It’s a matter of filler and sanding. Enough of that medicine and a professional paint job, and the plane will look perfect, even though the structure beneath is below sub-standards. With aluminium that is not possible, every imperfection will show. An impeccable RV (or any other metal airplane) really is a true masterpiece, while a good looking Lancair may very well just be the result of a year of sanding and tons of filler. My Onex is polished aluminium, nothing is hidden there but it looks good, so I’m getting better
It’s like one at Vans airforce have in his signature: It’s not skill or craftsmanship that finishes an airplane, it’s the will to do so. That really is true, and to find that will can be hard sometimes after a big mistake.
