The main point usually made on these type of threads is an away fan sitting in a home section, not wearing colours and keeping quiet, they wouldn’t draw attention to themselves and maybe wouldn’t even get noticed.
Most complaints are when an away fan is over celebrating their team’s goal and...
I saw a kid with a West Ham t shirt in the WSU, he was sitting not far from me in the row below mine, didn’t jump up and celebrate any of their goals, I wouldn’t have noticed him if he didn’t have the t shirt on.