If you have used the analytical tools available, and understand the interpretation, the results you get are pretty accurate. I use the various Admixture Tools on Gedmatch.
Personally, I don't rely on the interpretation by FTDNA, Ancestry, or others.
You are of course entitled to your opinion.
I have over 200 posts on the Ancestral Family Tree DNA Testing board. Perhaps if you read them you would not be so quick to criticise me, and incidentally would not have made some of the assumptions you have about me. Still there you go each to their own.
I think you need to take a deep breath and calm down.
I doubt all those individuals have used the Admixture Tools available, or understood them correctly. Clusters overlap and it can be easy to receive the erroneous results.
For instance, I have 4% Ashkenazi Jewish in my FTDNA results, I don't have any Jewish ancestors, but with a little research I learned Ashkenazi Jews overlap with Italians and Greeks. This is because they all share East Med DNA.
Most likely that element of my DNA is from the Romans.
So, in summary, most results aren't totally wrong, it's the tools used and the
interpretation of the data.