I pressure cleaned the front section of my garden wall today. It was covered in fungus and all sorts of growths but it has come up nice. I was packing up when my new neighbour came over to me. He wasn't ammused and looked very angry with me. I was warned about this neighbour by my previous neighbours who sold him the house. They told us that they hated him and we would have problems with him. They said that they didn't want to sell it to him and wouldn't have, if they had more time to sell their house. Anyway, he said I'd turned his wall green. I was confused. I'd done my best to make sure nothing flew into his garden and I didn't touch anything of his. I doubled checked when I'd finished so had thought everything was fine. Then he motioned me to come into his back garden. Now I was really confused. I hadn't done the back garden wall. Now he pointed to his wall and said 'look! I've just cleaned that wall and now you've got it a mess'. A small section was damp across the top. I think 'yeah I've made that damp'. I wasn't sure exactly how I had but logic dictated, it was a sunny day, I was the one with the water, it must have been me. I said 'yeah it looks like I've made it damp but I'm not sure if I've turned it green'. Then he said 'you've sprayed the coping stones on the top and it has washed down and covered my wall. He had assumed I had cleaned the back garden wall and coping stones that were around that wall. They are taller than him so he couldn't see if I'd cleaned them or not, he had just assumed I had since he saw me earlier cleaning the walls. I hadn't, and told him. I hadn't cleaned the opposite side of that wall, I also hadn't cleaned the wall to the side of it. The wall I'd cleaned was a wall over the other side of that green wall. It was the opposite side of that wall too so it would have been impossible for anything of mine directly hitting that green wall. I'm thinking the only way I could have made it damp was the mist I was kicking up or I've hit the opposite side of that wall with a burst by accident. The opposite side was dry though. I was just using water and no chemicals. Anyway, could I have turned it green? I tried explaining that I'd no idea how I'd turned it green and I hadn't been near that wall but he wouldn't let me talk. He just kept saying 'I'm not arguing with you, you've turned it green!'. I'd have gladly cleaned it for him but he just wanted to tell me what I'd done and not hear me out. In the end I just headed off, he wouldn't let me speak. It looks to me like its stained and not something that has washed down. I do know he'd recently removed some vines from that wall that were planted by the previous owners. Also below the bright green are some faded green patches. Would they come up a brighter green if wet? I'm just looking for some advice. If I have made it green how could it have happened so I can avoid making this mistake in the future. Cheers.