I am not surprised by the number of complaints about this product. We experimented with this relatively new product and it has been a disaster.
This decking cannot be kept clean.
I have tried the Corte Clean product. It barely affects the spots on the deck.
I have used a power washer and it is very easy to adversely affect the Timber Tech surface. Power washing does little to clean our deck. A deck that gets a substantial amount of sun.
This company should not be making decking if this is the best they can do.
We wished we had used treated wood. It would have looked better and wouldn't have the constant maintenance this product demands. And even with the the maintenance the deck doesn't clean up.