On brain work, it's hardly such when the effect is binary (dead or not) and deterministic (fixed radius, 100% chance of dying); it's just a matter of memorizing the radius and getting really annoyed when you're off by a pixel or two. A more desirable invisible "keep away" effect would be gradual (such as not to be too punishing) and have a much wider radius (to make the whole keepaway thing more relevant than moving a few pixels; enforcing tight movement is the red particles' job); of course, KS is incapable of this (though an obvious choice would be attractors/repellents, usable for pushing the player towards other particles, and possibly by the player for quick escapes and floating).
On doing reds' job, that's already the case, at least by my principles, and in practice for people with ks superknowledge and crazy good eyes. If you want uniqueness through charm, you already have the lies about them being safe (that's charming, right?).
On tidiness, I guess that applies, but a visible effect radius wouldn't have to be bright and shiny.
On color, sure, but my issue is more with steering away and undershooting due to my horrible lack of ks superknowledge and crazy eyes.