No I don't test before hand but I inform the customer first I'm there to clean them the condition to age is not down to me
I think had you pressure washed you may have got a bit more of the old colour off - over the years I've had 3 maybe 4 like this customers usually happy as I say it's a clean - I know one got the roof resprayed a few months later
The worst ones are where builders match the dirty tiles with black or grey then we clean them and find out they are red or sand colored, so the customer has a two tone roof
Darran