The earth rotates at 1000 mph or something like that and this seemingly big number makes FE'rs think we should be feeling the effects of that intuitively. The speed of that system is irrelevant though. What matters is it's rate of rotation which we all know is only once per day. This is extremely slow and the earth is extremely large so objects that are affected by the coriolis need to be under it's influence for long amounts of time or be traveling over relatively large areas.
A toilet flushing is neither of those things. Toilets do drain in a clockwise or counterclockwise rotation most of the time but this is because of the shape of the bowl or the direction in which water shoots out from the top of the bowl. Some toilets have no rotation at all.