Whats the criteria for judging this? I can think of few criteria that help narrow it down a bit but it's by no means definitive and would not be uttered amongst fellow PA members. Unless there is a positive test, and the best testing would be by OCT, then any given lifter in tested Fed is entitled to a presumption of cleanliness. In reality there will be a percentage who are not.
Its hard to envisage much of an incidence of usage in lifters ranking up to or including A grade, although some people are just so fucking useless and stupid I guess it is possible. There's always some fuckwit who puts a 13B in a Datto 120Y and calls it a race car.
If all E2 were subject to OCT testing at the same time, then my guess is that there would be about a 10-15% probability of finding a grub. For E1 there might be 20-25% probability of finding a grub if all lifters were tested simultaneously.
For WL, it's much easier to pick (ie presume something is suss) without testing. There is a clear break that separates plainly awesome from scary awesome.