I personally find 100nl to be the borderline. You get a mixture of good and bad regs at this limit.
Generally at 50nl and below, everyone is dreadful. They might be able to spot the leaks in our game, but they dont know the correct adjustments to make.
When it comes to other people seeing me play, I am normally aware of my general image at the table, its not something to worry about that much, as most people play too many tables, so cant pay enough attention to anything but their own hands. If i have just blown of 2 stacks on crazy bluffs or something, I will vbet super thin in the next few hands and bluff very little.
Same as if my hud stats are showing i have a 20% 3bet for that table I will 3bet much more for value and way less as a bluff.
When it comes to playing against people when I am a unknown, I find I can take really fishy lines early on, also run some big bluffs. Say for instance i check calls twice with KT on K43hhA6h and I am OOP, I will 3/4 lead river, turning my hands into a bluff. Its known to be a fishy value line so he only calls with the very top of his range. He wont view it as strong though once he finds out im a reg.
There are tonnes of things I think i do, its just very hard to put into words what it is I actually do, but bet sizing and ranges are something I put a lot of thought into.
If your playing vs me and you rep a narrow/weak range, expect to get lots of money thrown at you