stars are not blurry circles hanging in space
they should look like points of light.
look at the sun. well--not directly. but look at some high-quality pictures of it. that is a decent example of a close-up star. it is a clearly defined, sharp shape, giving off very thin beams of light.
look into the night sky at a particularly bright star, like sirius. it gives off a glow but the glow is incredibly subtle. what is more noticeable is the actual hard shape of the star itself.
when you see blurry light halos around a point of light, it means you're looking at it as it (the light itself) is surrounded in a fog or cloud of some sort. this is because the water (or dirt, etc) molecules floating in the air are reflecting light as well.
stars are surrounded by lightyears of absolute void, and darkness--what is there to reflect light and make a halo? nothing.