Particle remnants left on canvas when fading

Particle remnants left on canvas when fading

This blog article: http://rectangleworld.com/blog/archives/871 explains
why, in certain situations ugly grey remnants can be seen on canvases.
The TL:DR of this article is that when you use a dark, translucent
rectangle to give your particles trails that gradually fade out, rounding
errors mean that eventually, the canvas will get stuck at dark grey and
will never fade to black.
I wanted to throw this dilemma out to the ingenious community of
StackOverflow to see if they have any clever solutions (other than direct
pixel manipulation), which would solve the issue.