Well its almost without doubt that Florence Griffith-Joyner was doping. From average (among elites) to elite among elites in such a short time... unless some technical error was corrected that caused it (which they never claimed), there's little else to suspect.
But whatever. I think that Bolt is legit. He's an amazing runner. His 100m splits in the 200m are faster than some of the Olympians qualifying times for the 100.