What a tracer should look like (before spazzing just look).

[Das Attorney]

There is no way that the human retina could absorb enough light from a passing incandescent object (like a tracer) to perceive any kind of impression that it is bending relative to the vector of the eye (and said owner of the eye).

Maybe if you fired a tracer round past a fly (for example), it could pull in enough light to detect a change in direction relative of the tracer round to the fly's own position if it were to move away quickly. But then, because it takes in more visual information per unit of time, it would see a vastly improved impression of the tracer, with a correspondingly short trail (less flare effect). Therefore; even a creature (and it would have to be a creature - not a human pilot) with vastly improved eyesight could not see tracers as bending.

Light (and interpretation of light) just doesn't work that way.

As for sources: I can't give you any right now. But if it will settle this physics lunacy, I will be/will not be (un)happy to cobble together a (certainly) boring and (utterly) (un)necessary post. I will do it in my own time, because it is so mind numbingly dull. I will look forward to people disputing it as soon as I (don't) post it.