I don’t mind people flushing their black tank after dumping. The trigger for me is when they start shooting the breeze with someone, or have some complicated dump hose packing method that takes forever. Last time we went camping there were some ladies in an RV in front of us. They kept talking to each other which slowed down the process, then they get in their rig and it just sits there. Finally got out of my truck and walked up to their window to see them talking. Did the universal WTF sign language by putting both my arms up in the air. They just looked at me like they had no clue there were 10 RV’s waiting behind them. Cleaning the black tank bothers me the least.