For band 1, the penetration depth will usually be between 1 and 10 meters. If the water has a large turbidity spike below 10 meters, the spike is unlikely to be seen by a satellite. For very shallow clear water there is a good chance the bottom may be seen. For example, in the Bahamas, the water is quite clear and only a few meters deep, resulting in an apparent high turbidity because the bottom reflects a lot of the band 1 light. For areas with consistently high turbidity signals, particularly areas with relatively clear water, part of the signal may be due to bottom reflection.
Clouds are also problematic for the interpretation of satellite derived turbidity.
Cloud removal algorithms perform a satisfactory job for pixels that are fully cloudy. Partially cloudy pixels are much harder to identify and typically result in false high turbidity estimates. High turbidty estimates in normally low turbidity areas and near clouds are suspect.