There's a distinct difference going on with Nazis in Europe vs the USA..
A friend of mine is a cop, specialized in all matters of football supporters.
From there..... Yes, there are Nazi recruiters trying to infiltrate the scenes. But why? Nazis have it quite more difficult in Europe than they have in the US.
In the US they can openly recruit. The first amendment protects them from consequences regarding the hatred they spilling around.
And yet still..... The racism in our European stadiums is to be treated with caution. Most of these emotions are fueled by pure club rivalry. It certainly is not okay, and should not happen. But it is also exaggerated. Factually it doesn't make any sense anyway. I am willing to claim, that there is not one professional football club that does not have foreign players or players of another color than the natives. At least the teams in the various age groups behind the pro roster have them.