Using liquid hypo is standard practice in house washing,...you need to explain to the customers that the "smell",...won't last very long,...in reality if there is much more than a sensation of bleach odor, it was most likely applied too strong, which equal wasted material and possible browning of plants. It is the hypo in the mix that kills both the black and green mold and also makes bug crap stains disappear. If a customer told me what to use or what I couldn't use I would explain first and then they could decide to go with my plan or call someone else. I am the professional not the customers,..and you need to understand that and stand behind it.
I agree, If the customer thought they knew more than I did "I would ask them why they called me". You are the professional, not the customer. Many times the customer would read an article or search the internet and think they were an expert. There are products to mask the smell of bleach. I carried one "Lemonator" but most felt they could not justify the price, and yes it did work well. What do you think would happen if you took your car to the shop and told the how to repair it? That is what I thought.