you should watch level 2s more closely. just took a picture of market makers loading at the ask painting the 0002s red
it's quite a tactical skill.
they hit the ask, and a trade gets executed at .00025, while the bid is 0001 and the ask is 0002, it shows green, then all the 0002s get bought at the ask but painted red.
it's fun to leave crumbs and it's fun to follow the crumbs