Actually, now that I think about it - not quite true Peter.
I first did Judo as a kid and I guess I just trusted it _ my mom sent me. After a while I just found that I wasn't learning - I was just fodder for the bigger kids - and eventually quit. I did a lot of work - sweat etc - but learned very little. They taught very little. And I figured that out for myself.

Then, I found Aikido and they actually taught stuff. It was Tomiki Aikido and it emphasised effectiveness. My teacher was a prison officer and used it often. He was also black belt Judo and he taught us good Judo waza. I loved it and was hooked. We learned katas, and then we studied how to make the individual waza work (Tomiki and Judo). Then I discovered my teacher (Barry Vigrass) was also shodan in what he then called - Ueshiba Aikido - so off I went to find out what that was - Aikikai.

Back then, 1980s, I had lots of 'material' to compare. Many teachers were just not that good. More than a few clubs had teachers who were just kyu grades and it was OK for them to be not so good, but actually, they were usually pretty good for kyu grades. I have seen far worse dan grades in more modern times. My teacher encouraged us to train in different places and we did - I like to think it made a difference. In those days, it was rather taboo to train elsewhere so we had to be careful - everyone was so protective and I still don't really know why. At one point I was doing Tomiki, Aikikai, Judo, and Jujutsu, and Wing Chun all at the same time and I could not tell the teachers I was doing other stuff. I just had to keep my mouth shut (except to the Tomiki teacher). I went on all sorts of courses and got to see many different people so I think that is where I learned to distinguish between who has the skill ...or not. And it cost me a fortune! Sometimes I wonder if I have just wasted my time!