In order to get reads on people online you need to be playing against people who have some sort of understanding of the game.
Then you can put them on a range of hands, and extrapolate what they are likely to play.
You also pick up patterns that people do, like bet amounts.
If you play a lot of freerolls
or micro-stakes tournaments you are often against people who do not
understand the game or do not care. They do really crazy stuff so reads are very difficult or misleading.
That is, they don't understand position or the gap concept so the strength of their hands is masked by ignorance.