I think once you accept that there are those at the very top level using unfair means to win, it becomes naive not to realise that it must be well-nigh impossible to win without those artificial advantages. Thus, you have to assume virtually anyone who wins is bent.
Think about it: Russia was running a state-sponsored doping scheme and only came fourth in the Olympic medals table. What does that suggest to you? It's essentially an arms race that forces everyone to use those means just to compete, so what else are people going to do?
It doesn't particularly bother me, either. What bothers me is the hypocrisy and naivety of imagining that it's only those guys who cheat and that 'our' guys must be fine.