Exactly.
We\'ve seen trainers accused of cheating that have 1-2 positives in their lifetimes, for drug amounts definitively too small to remotely be able to affect a horses performance.
This is also going to increase (picogram, \"on the dust in the air\", transfer from humans-type positives) as trainers are restricted to using less pharmaceuticals (generally predictable levels of positives in most horses, known levels of drug that can affect performance) and more \"natural\", \"holistic\" stuff.