The Russians, definitely not. They were known to have state sponsored doping programs AND ran very fast. That pushes the "probably doping" percentages up into stratospheric levels.
I often find 1 in 1000 works for reasonable levels of when to worry about something. Arbitrary, but it fits well for me. I'd say the odds of either of those two being clean as less than 1 in 1000 by a wide margin. Probably the same for FloJo, but I don't know her history as much.
Hassan, I'd put her (obviously arbitrarily) at around 1 in 500 to 1 in 1000 chance she is clean. I haven't heard much about shady agents or shady training partners or other out there claims. If there are more of those that I haven't been awared of, that would shift my opinion further. Her performances at NOP got much better, but as described she lost weight and her performance improvement is consistent with that. I don't think her doping status changed at NOP. If she was doping, she was doing so before and continued. She did not start at NOP. So enough to be very skeptical, but also at a level where I will still "reserve judgement" and not talk about her as if she is a doper. Many of them eventually fall.
My doping process goes something like this:
1) Fast Times = automatically suspicious, but willing to without hold judgement
Add in the below and I basically think of them as doping:
2) Associations with known dirty training groups/partners - doping
3) Highly inconsistent performances or long disappearances without explanation - more or less think of them as doping
4) History of missed tests
5) Originate/train in Russia/China/ NK/Islamic Countries
Probably some other things too but those are jumping out at me.
I too, would have difficulty buying a 12:30 5k. Even moreso a 12:00 5k. It would depend on many factors, but it's within the realm for possibility for a clean athlete (I'm willing to believe that the 95th percentile of VO2 and of fractional utilization are likely clean values). I'd obviously always be skeptical of such a performance, but hopefully an athlete of that caliber would go above and beyond to prove they are not doping.