I've known two guys, who were rumored to have doped. I watched one of them come out of absolutely nowhere to race a local D1 meet unattached, and they ran something like 8:0X for 3k outdoors in late Feb or early March. Homeboy just looked...unnatural running out there, as if he was just sitting on a red line the entire race. Then last year he pops up in another small road race and takes home an easy $1000. Both times, the same guy just disappeared into obscurity, and never touched any races that had either drug testing, or served as qualifiers for big USATF races. He just stayed under the radar. The accusations against him were made by one-time teammates and close friends.
The other guy who was accused of drug use ended up becoming a good friend of mine. He came into the cross hairs of his accusers because of what seemed like freakish improvement over the course of one season. However, all anyone had to do was sit down with him and learn that he had completely turned his life around, and made the tough choices necessary to start reaping the benefits of his unbelievable talents. No one who spent time training with him, racing with him, or hanging out with him ever knew him to act suspiciously or use any kind of drug.
I never forgot the two. One unjustly accused because of simple improvements and good decision making, while the other popped in and out of obscurity to claim prize money or bragging rights, and always just LOOKED wrong on the track.
Some of us follow the sport and its performances, then think of the folks we know in our own circles that we believe to have doped. We watch the top level runners, guys like Ramzi, or that Russian woman who won 3 high-level mile races last year in the same week (forgot her name), and immediately think of those other ridiculously unnatural performances that we've witnessed before. Then we air our frustrations and accusations on this here message board, knowing that they are not likely to ever be caught by any drug test that WADA is able create. Every once in a while, we get the pleasure of seeing someone who needs to get caught, go down in flames.
It's as simple as that. The accusers on this board are not always just flinging uninformed slander around.